Useful person as a worker many upset (8)
I believe the answer is:
handyman
'useful person' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'a worker many upset' is the wordplay.
'a worker' becomes 'hand' (hand is a kind of worker).
'upset' indicates an anagram.
'many' is an anagram of 'yman'.
'hand'+'yman'='HANDYMAN'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for handyman that I've seen before include "One hired to do odd jobs" , "One employed to do odd jobs" , "Repairer" , "Jack-of-all-trades" , "Odd-jobber" .)