A hundred presents in boxes (7)
I believe the answer is:
coffers
'boxes' is the definition.
(coffer is a kind of box)
'a hundred presents' is the wordplay.
'a hundred' becomes 'C' (Roman numeral).
'presents' becomes 'offers' (I've seen this before).
'c'+'offers'='COFFERS'
'in' is the link.
(Other definitions for coffers that I've seen before include "Treasure chests" , "containers" , "Financial reserves" , "Treasury box" , "Funds, financial resources" .)