Backer in to supply fruit (7)
I believe the answer is:
tangelo
'fruit' is the definition.
(I know that tangelo is a fruit)
'backer in to' is the wordplay.
'backer' becomes 'angel' (an angel is a financial backer).
'in' indicates putting letters inside.
'angel' placed inside 'to' is 'TANGELO'.
'supply' is the link.
(Other definitions for tangelo that I've seen before include "Citrus fruit hybrid" , "fruitful merger?" , "Hybrid fruit; eat long (anag.)" , "Citrus hybrid - goal net (anag)" , "one cross, sour" .)