Formal bid or offer (6)
I believe the answer is:
tender
I believe this clue is a double definition.
'formal bid' is the first definition.
(I've seen this in another clue)
'offer' is the second definition.
(tender can mean to offer something)
(Other definitions for tender that I've seen before include "Delicate sort of bid" , "easily crushed" , "Former railway vehicle is sensitive" , "Supply ship" , "Offer as payment; boat" .)