Daughter is a tree-hugger, endlessly in dispute (8)
I believe the answer is:
disagree
'dispute' is the definition.
(I've seen this before)
'daughter is a tree-hugger endlessly' is the wordplay.
'daughter' becomes 'd'.
'tree-hugger' becomes 'green' (both can mean an environmental activist).
'endlessly' means to remove the last letter.
'green' with its final letter removed is 'gree'.
'd'+'is'+'a'+'gree'='DISAGREE'
'in' acts as a link.
(Other definitions for disagree that I've seen before include "Beg to differ" , "Have conflicting opinions" , "Dire ages (anag.)" , "Contradict" , "Be at variance" .)