Managed to attract endless resentment (7)
I believe the answer is:
rancour
'resentment' is the definition.
('rancour' can be a synonym of 'resentment')
'managed to attract endless' is the wordplay.
'managed' becomes 'ran' (I've seen this before).
'to attract' becomes 'court' (as in a phrase like 'to court controversy').
'endless' means to remove the last letter.
'court' with its last letter taken away is 'cour'.
'ran'+'cour'='RANCOUR'
(Other definitions for rancour that I've seen before include "Bitter feeling or ill-will" , "Bitterness or resentfulness" , "Long-lasting bitterness" , "Entrenched enmity" , "Hard feelings" .)