Engine part -- offer to enclose information (3,3)
I believe the answer is:
big end
'engine part' is the definition.
(I've seen this before)
'offer to enclose information' is the wordplay.
'offer' becomes 'bid' (bid is a kind of offer).
'to enclose' means one lot of letters goes inside another.
'information' becomes 'gen' (gen can informally mean information).
'bid' placed around 'gen' is 'BIG END'.
(Other definitions for big end that I've seen before include "that'll be needed to get engine going" , "Part of car engine's connecting rod" , "favoured by Lilliputian rebels" , "essential to Chitty Chitty Bang Bang?" , "favoured by Blefuscudians" .)