On small stages (4)
I believe the answer is:
legs
'stages' is the definition.
('leg' can be a synonym of 'stage')
'on small' is the wordplay.
'on' becomes 'leg' (cricket term, fielding positions).
'small' becomes 's' (abbreviation - e.g. clothes size).
'leg'+'s'='LEGS'
(Other definitions for legs that I've seen before include "Lower limbs" , "associated with 11 in game" , "Members" , "Stages of a journey" , "Sections of a journey or course" .)