Casual worker appears after not working (7)
I believe the answer is:
offhand
'casual' is the definition.
(synonyms)
'worker appears after not working' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'appears after' is a charade indicator (letters next to each other).
'not working' becomes 'off' (I've seen this before).
'hand' put after 'off' is 'OFFHAND'.
(Other definitions for offhand that I've seen before include "with a careless manner" , "Nonchalant" , "Casual or curt, like discarded glove?" , "Of speech, casual or curt" , "Cavalier" .)