Superb fish served by one worker (9)
I believe the answer is:
brilliant
'superb' is the definition.
(I know that superb can be written as brilliant)
'fish served by one worker' is the wordplay.
'fish' becomes 'brill' (brill is a kind of fish).
'served by' becomes 'i' (I am not sure about this - if you are sure you should believe this answer much more).
'one worker' becomes 'ant' (worker is a type of ant).
'brill'+'i'+'ant'='BRILLIANT'
Can you help me to learn more?
(Other definitions for brilliant that I've seen before include "Vivid; clever" , "Of surpassing excellence" , "Magnificent" , "Very bright; marvellous" , "Brainy" .)