not really, a cm of topsoil wont stop the old grass growing through. if most of the lawn is ok why not sow seed in the bare patches so it 'fills' out.
but you will have to remove any perennial weeds in the lawn as again a shallow topdressing os soil wont deter the weeds.

welcome to GoY too by the way.

Thank you I don't really have a problem with weeds. My lawn has sunk about an inch over the years and a drain runs across it. With clay soil and a dry summer I always get a dead annoying stripe across it. So I wanted to know if I could lay a layer of topsoil and seed and that it would take properly. It will be a bonus if the original grass grows through .

If you can then could you dig a little deeper down along where the pipe runs, take out some of that clay and back fill with decent topsoil, if you do then leave the topsoil to settle for a week then re firm it add some more top soil to get it level and then seed , I have had similar situations over the years on jobs and have always found this works well, however if you were to get that stripe reappear in drought situations then I would keep this area well watered.