Part with a coin (3)
I believe the answer is:
bit
I believe this clue is a double definition.
'part' is the first definition.
(bit is a kind of part)
'a coin' is the second definition.
(I've seen this before)
'with' is the link.
(Other definitions for bit that I've seen before include "Boring tip of a drill" , "Small piece - used teeth" , "Cutting piece of a drill (3)" , "gripped" , "Part of 21 across" .)