Having served as a cleaner, finished (4,3)
I believe the answer is:
done for
'finished' is the definition.
(synonyms)
'having served as a cleaner' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'one' and 'one' is located in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for done for that I've seen before include "in serious trouble" , "finished" , "Ruined" , "condemned" , "killed" .)