Drink too much? That’s a coincidence (7)
I believe the answer is:
overlap
This clue is a double definition.
'drink too much?' is the first definition.
(to over-lap could be to lap or drink too much)
'coincidence' is the second definition.
(I know that overlap is a type of coincidence)
'that's a' is the link.
(Other definitions for overlap that I've seen before include "Partially coincide" , "Put extra cover on" , "Outflank" , "bit of a coincidence" , "have something in common" .)