Upset group of workers left when trophy withdrawn (5)
I believe the answer is:
cutup
'upset group' is the definition.
The definition suggests a singular noun which matches the answer.
'workers left when trophy withdrawn' is the wordplay.
I cannot really understand how this works, but
'workers' could be 'tu' (abbreviation for trade union) and 'tu' is present in the answer.
'trophy' could be 'cup' (cup is a kind of trophy) and 'cup' is found in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for cutup that I've seen before include "Distressed" , "being overtaken in dangerous manner" .)