Discharged sailors loved mischief (8)
I believe the answer is:
'discharged' is the definition.
(I've seen this before)
'sailors loved mischief' is the wordplay.
'sailors' becomes 'abs' (AB is short for able seaman).
'mischief' indicates anagramming the letters.
'loved' is an anagram of 'olved'.
(Other definitions for absolved that I've seen before include "Forgiven" , "Forgave sins" , "Declared free (from guilt)" , "1 [LET OFF]" , "Cleared, exonerated" .)