Lay out fashionable underwear (6)
I believe the answer is:
invest
'lay out' is the definition.
(I've seen this before)
'fashionable underwear' is the wordplay.
'fashionable' becomes 'in' (similar in meaning).
'underwear' becomes 'vest'.
'in'+'vest'='INVEST'
(Other definitions for invest that I've seen before include "Lay siege" , "as Greeks did to Troy?" , "Eg, buy stocks and shares" , "Buy shares; besiege" , "Put money into a company" .)