Partly coincide in time (7)
I believe the answer is:
overlap
'partly coincide in time' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for overlap that I've seen before include "Lie partly on top of" , "Extend beyond edge of a thing and partly cover it" , "Partly hide" , "Extend on top of" , "bit of a coincidence" .)