In "The Painted Door" by Sinclair Ross, Ann has a heightened awareness of time, its passing, and the effect it has upon her life. Either time, as represented by the clock, passes too quickly or not quickly enough.
On the one hand, Ann wants the time to pass quickly so that she and her husband, John, will finally be able to pay off their mortgage and enjoy life together. On the other hand, she's worried that when this happens, she'll be too old to enjoy life. Trapped by time, Ann is caught between a rock and a hard place.
Ann can do a number of things to make her feel that she's in control of time, such as giving the bedroom door a fresh lick of paint or making herself feel younger by having an affair with Steven. But one thing she can't do is turn back the clock completely.
Try as she might, she will never be able to arrest the aging process. Time will continue its inexorable march forward, and there's absolutely nothing that Ann can do about it. All she can do is to keep herself and her surroundings, as represented by the eponymous painted door, fresh. Even so, the clock will still tick on.