It was the Addicks who started the game on the front foot. Riva Casley made a superb diagonal ball out wide to Ellie Dorey, but the Coventry defence were quick to make the challenge and clear the danger.
A minute later Coventry tested the Charlton defence as they surged forward, but Rachel Newborough did well to pinch the ball and stifle the attack.
Charlton gained an early lead in the eighth minute after some excellent build-up play. Jenna Legg intercepted a pass in the Coventry half to set up the attack.
The midfielder squared the ball to Clifford, who then passed to Dorey. Dorey neatly fed the ball through to Newborough, whose drilled cross bounced back to Clifford at the edge of the box who fired into the bottom corner to give Charlton the lead.
Soon after Coventry restarted the game, Clifford could have got her second in as many minutes.
Grace Coombs picked out Lois Heuchan on the left-wing, her cross evaded the head of Charlie Estcourt, but a miss-kick by a Coventry defender allowed Clifford to strike, but her effort was blocked.
In the 13th minute, Clifford tried to feed the ball through to Dorey, but Sue Wood was quick off her line to clear.
Coventry had their first shot in the 14th minute, but Fiona Worts’ strike was well over the bar.
The visitors eased their way into the game, a free-kick floated into the area in the 20th minute was dealt with calmly by Charlton.
Coventry looked to go forward again two minutes later, but Heuchan put in a strong tackle to regain possession.
Clifford hit the bar in what would have been a spectacular goal in the 27th minute.
Newborough fed the ball to Clifford, who turned her player and took aim from 25 yards out, but her powerful strike cannoned off the crossbar. The ball dropped to Heuchan in the six-yard box, but her shot was over.
Coventry started the second half much brighter and pressured the Addicks.
Five minutes into the half a ball was whipped into the Charlton box but evaded the head of Worts.
Coventry won a free-kick at the edge of the box, as Lilli Maple’s tackle was deemed a foul by the referee. The free-kick is deflected out for a corner, which the visitors couldn’t capitalise on.
The visitors continued to dominate possession, winning another free-kick. Casley headed the ball out for a corner, which Maple then cleared.
The Addicks had a brilliant chance with twenty minutes left, Dorey did brilliantly to intercept a goal kick and feed the ball through to Charlie Devlin who rounded the keeper and had her drilled effort cleared off the line into the path of Newborough who struck wide.
Shannon O’Brien powered forward in the 73rd minute and sent in a driven cross, but Clifford did brilliantly to put pressure on the Coventry striker, and the ball went out for a goal kick.
Charlton won a free-kick in a dangerous position with ten minutes left, but Clifford’s effort was just too high.
The Addicks had another chance to make it 2-0 when Devlin threaded the ball through to Dorey, but her strike was straight at Wood.
The sucker punch came in the 89th minute. Charlton failed to clear as Coventry kept putting balls into the box, two Coventry players were free in the box with Newborough clearing Jodie Bartle’s header off the line before Dermody scrambled the ball into the back of the net.
Charlton are straight back to action on Wednesday when they host Bristol City in the Continental Cup at The Oakwood, 7.45pm.
Charlton: Startup, Newborough, Coombs, Dorey, Clifford, Casley, Estcourt, Legg, Maple (Wilson 81), Heuchan (Devlin 54), Mustaki
Subs (not used): Salgado, Gotch, Espinosa, Griffin, Eggesvik
Goal: Clifford 8
Coventry: Wood, Crackle, Miles, Bartle, Morgan (Johnson 77), Morris, Weston (Anderson 34), Merrick, Worts (Dermody 68), Hughes, O-Brien
Subs (not used): Riden, Axten, Gardner, Chong
Goal: Dermody 89
Bookings: Merrick 71