One espousing leather trousers? (6)
I believe the answer is:
single
'one' is the definition.
('single' can be a synonym of 'one')
'espousing leather trousers?' is the wordplay.
'trousers?' indicates a hidden word (to trouser can mean to contain or hold).
'SINGLE' is hidden in the letters of 'espousing leather'.
(Other definitions for single that I've seen before include "Not in a relationship" , "Still miss" , "Like bachelor" , "Just one, or unmarried" , "One-way ticket" .)