Manage pain I've unfortunately taken on board (7)
I believe the answer is:
achieve
'manage' is the definition.
(thesaurus)
'pain i've unfortunately taken on board' is the wordplay.
'pain' becomes 'ache' (ache is a kind of pain).
'unfortunately' indicates an anagram (a bad or unfortunate spelling).
'taken on board' is an insertion indicator.
'ive' is an anagram of 'iev'.
'ache' placed around 'iev' is 'ACHIEVE'.
(Other definitions for achieve that I've seen before include "Attain (goal)" , "Have ice (anag.)" , "Manage to get" , "Consummate" , "Bring to a successful outcome" .)