Contribute in hope of a return (6)
I believe the answer is:
invest
'contribute in hope of a return' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for invest that I've seen before include "Lay out in expectation of profit" , "Contribute money in hopes of financial return" , "Contribute money in hope of a return" , "Place money in a scheme" , "as Greeks did to Troy?" .)