Dumb ideas include offer (3)
I believe the answer is:
bid
'offer' is the definition.
('bid' can be a synonym of 'offer')
'dumb ideas include' is the wordplay.
'include' indicates a hidden word.
'BID' is hidden in the letters of 'dumb ideas'.
(Other definitions for bid that I've seen before include "Take part in auction" , "Attempt, offer" , "Make an offer at auction" , "Propose a payment" , "Make offer for 20 Down" .)