Champion's boy in distress (7)
I believe the answer is:
paladin
'champion's' is the definition.
(synonyms)
'boy in distress' is the wordplay.
'boy' becomes 'lad' (informal term for boy).
'in' is an insertion indicator.
'distress' becomes 'pain' (I've seen this before).
'lad' placed within 'pain' is 'PALADIN'.
(Other definitions for paladin that I've seen before include "Historical knight" , "Heroic knight - aid plan (anag)" , "hero" , "Chivalrous knight" , "One of the twelve peers at Charlemagne's court - heroic champion" .)