Worn-out biro held by good man (5)
I believe the answer is:
spent
'worn-out' is the definition.
(synonyms)
'held by good man' is the wordplay.
'held' becomes 'pent' (both can mean imprisoned).
'by' is a charade indicator (letters next to each other).
'good man' becomes 's'.
'pent' after 's' is 'SPENT'.
'biro' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for spent that I've seen before include "Worn out having paid out money." , "Splashed out" , "Drained of energy - or paid out" , "Used up; exhausted" , "Worn out - after shopping?" .)