Casual worker, unwell earlier (7)
I believe the answer is:
offhand
'casual' is the definition.
(synonyms)
'worker unwell earlier' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'unwell' becomes 'off' (as in feeling off).
'earlier' says to put letters next to each other.
'hand' put after 'off' is 'OFFHAND'.
(Other definitions for offhand that I've seen before include "Without thought" , "Of behaviour, casual or curt" , "Without consideration" , "Casually rude" , "Cavalier" .)