Reprobate tribe disbanded during occupation (9)
I believe the answer is:
libertine
'reprobate' is the definition.
(I've seen this before)
'tribe disbanded during occupation' is the wordplay.
'disbanded' is an anagram indicator (I've seen this in other clues).
'during' indicates putting letters inside.
'occupation' becomes 'line' (synonyms).
'tribe' anagrammed gives 'berti'.
'berti' put within 'line' is 'LIBERTINE'.
(Other definitions for libertine that I've seen before include "Rakish" , "Person who live immorally - sounds free" , "reprobate" , "of roues" , "Roue" .)