Constant bids for funds (7)
I believe the answer is:
coffers
'for funds' is the definition.
(coffers can mean funds or reserves)
'constant bids' is the wordplay.
'constant' becomes 'c' (mathematical abbreviation).
'bids' becomes 'offers' ('offer' can be a synonym of 'bid').
'c'+'offers'='COFFERS'
(Other definitions for coffers that I've seen before include "Treasury funds" , "Financial resources or money boxes" , "Treasury boxes" , "Money-chests" , "Treasure chests" .)