Too much work: left to retire (6)
I believe the answer is:
troppo
'too much' is the definition.
Both the definition and answer are adjectives.
Perhaps you can see a link between them that I don't see?
'work left to retire' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'left' becomes 'port' (left side of a ship - opposite of starboard).
'to retire' says the letters should be written backwards (retire can mean to go back).
'op'+'port'='opport'
'opport' written backwards gives 'TROPPO'.
Can you help me to learn more?
(Other definitions for troppo that I've seen before include "too much when playing" , "Too much musical" , "Driven mad [STRINE]" , "too much for musicians" .)