Short sons in underwear (6)
I believe the answer is:
briefs
'underwear' is the definition.
(I've seen this before)
'short sons' is the wordplay.
'short' becomes 'brief' (similar in meaning).
'sons' becomes 's'.
'brief'+'s'='BRIEFS'
'in' is the link.
(Other definitions for briefs that I've seen before include "Sets of instructions for lawyers" , "CLOTHING" , "Orders" , "Gives (someone) essential information" , "Underpants for a lawyer" .)