Presents in boxes unopened (6)
I believe the answer is:
offers
'presents' is the definition.
(I've seen this before)
'boxes unopened' is the wordplay.
'boxes' becomes 'coffers' (coffer is a kind of box).
'unopened' means to remove the first letter (without opening letter).
'coffers' with its initial letter taken away is 'OFFERS'.
'in' is the link.
(Other definitions for offers that I've seen before include "Bids, tenders" , "Presents for acceptance or rejection" , "Presents for acceptance or refusal" , "Makes bid or tenders" , "volunteers" .)