Pins, for example, in two sizes (4)
I believe the answer is:
legs
'pins' is the definition.
(pins can informally mean someone's legs)
'example in two sizes' is the wordplay.
'two sizes' can mean two replacements for 'size'.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'in' is an insertion indicator.
'size' becomes 'l' (large clothing size).
'size' becomes 'S' (small clothing size).
'l'+'s'='ls'
'eg' put within 'ls' is 'LEGS'.
'for' acts as a link.
(Other definitions for legs that I've seen before include "Lower limbs" , "Sections of a journey or course" , "associated with 11 in game" , "Stages of a journey" , "Members" .)