Man collapsed with cry of pain (6)
I believe the answer is:
fellow
'man' is the definition.
(fellow is a kind of man)
'collapsed with cry of pain' is the wordplay.
'collapsed' becomes 'fell' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'cry of pain' becomes 'ow' (exclamation of pain).
'fell'+'ow'='FELLOW'
(Other definitions for fellow that I've seen before include "Colleague" , "Relating to a person in the same situation as oneself" , "Kind of associate, may be a traveller with communism" , "Senior member of a college or university" , "Informally, a man, or the other of a pair" .)