Valets possibly curse, seeing such clothing (8)
I believe the answer is:
menswear
'such clothing' is the definition.
(menswear is a type of clothing)
'valets possibly curse' is the wordplay.
'valets possibly' becomes 'men' (valets are male servants).
'curse' becomes 'swear' (synonyms).
'men'+'swear'='MENSWEAR'
'seeing' acts as a link.
(Other definitions for menswear that I've seen before include "Male clothes" , "Suits, trousers etc" , "Sort of clothing" , "Male outfits" , "For example, ties" .)