Fool the man in dress (6)
I believe the answer is:
clothe
'dress' is the definition.
('clothe' can be a synonym of 'dress')
'fool the man' is the wordplay.
'fool' becomes 'clot' (I've seen this before).
'the man' becomes 'he' (**).
'clot'+'he'='CLOTHE'
'in' acts as a link.
(Other definitions for clothe that I've seen before include "Dress (someone)" , "Equip" , "robe" , "Provide cover for body and limbs" , "apparel" .)