Rehabilitate star found in tree, drunk (8)
I believe the answer is:
renovate
'rehabilitate' is the definition.
(thesaurus)
'star found in tree drunk' is the wordplay.
'star' becomes 'nova' (nova is a kind of star).
'found in' is an insertion indicator.
'drunk' is an anagram indicator.
'tree' anagrammed gives 'rete'.
'nova' placed into 'rete' is 'RENOVATE'.
(Other definitions for renovate that I've seen before include "Modernise" , "Make as new" , "Restore to a previous or better condition" , "Renew" , "Bring back to pristine condition" .)