Bush finds credit in reserve (5)
I believe the answer is:
scrub
'bush' is the definition.
('scrub' can be a synonym of 'bush')
'credit in reserve' is the wordplay.
'credit' becomes 'cr'.
'in' is an insertion indicator.
'reserve' becomes 'sub' (I've seen this in other clues).
'cr' put within 'sub' is 'SCRUB'.
'finds' is the link.
(Other definitions for scrub that I've seen before include "Stunted growth" , "Clean - scrap" , "Eliminate" , "Curbs (anag.)" , "Take out - clean" .)