In bid, bolt down agreement (6)
I believe the answer is:
treaty
'agreement' is the definition.
(treaty is a kind of agreement)
'in bid bolt down' is the wordplay.
'in' is an insertion indicator.
'bid' becomes 'try' (I've seen this in other clues).
'bolt down' becomes 'eat' (I've seen this in other clues. I am not sure about the 'bolt' bit.**).
'try' going around 'eat' is 'TREATY'.
Can you help me to learn more?
(Other definitions for treaty that I've seen before include "Formal agreement between governments" , "Political or private agreement" , "Written agreement between two states" , "settlement" , "International agreement" .)