Strike for a share (5)
I believe the answer is:
whack
I believe this is a double definition.
'strike' is the first definition.
(thesaurus)
'for a share' is the second definition.
(whack can mean a share or contribution)
(Other definitions for whack that I've seen before include "Strike sharply" , "Resounding blow" , "Strike; specified share" , "Hard hit" , "Strike; share (slang)" .)