Influence is a hit (5)
I believe the answer is:
clout
This clue is a double definition.
'influence' is the first definition.
(I've seen this before)
'a hit' is the second definition.
(I've seen this before)
'is' acts as a link.
(Other definitions for clout that I've seen before include "Influence; heavy blow" , "A blow; powerful influence" , "weight" , "Old-fashioned garment" , "political muscle" .)