A conservationist almost giving consent (5)
I believe the answer is:
agree
'consent' is the definition.
(I know that agree is a more specific form of the action consent)
'a conservationist almost' is the wordplay.
'conservationist' becomes 'green' (I've seen this before).
'almost' means to remove the last letter (almost the whole word is kept).
'green' with its last letter taken away is 'gree'.
'a'+'gree'='AGREE'
'giving' acts as a link.
(Other definitions for agree that I've seen before include "Allow" , "Concur, acquiesce" , "Settle" , "Concur, coincide" , "Say yes to a suggestion" .)