American politician not ultimately giving consent (5)
I believe the answer is:
agree
'consent' is the definition.
(agreeing is a kind of consenting)
'american politician not ultimately' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'politician' becomes 'green' (eg member of the Green Party).
'not ultimately' means to remove the last letter.
'green' with its final letter removed is 'gree'.
'a'+'gree'='AGREE'
'giving' is the link.
(Other definitions for agree that I've seen before include "concede" , "Enjoy view in common" , "Say yes to a suggestion" , "suit" , "Have the same opinion" .)