Nosily picks up small coins (6)
I believe the answer is:
scents
'nosily picks up' is the definition.
(detects by smell - picks up with one's nose)
'small coins' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'coins' becomes 'cents' (cent is a kind of coin).
's'+'cents'='SCENTS'
(Other definitions for scents that I've seen before include "Distinctive odours, usually pleasant" , "Fragrances, smells" , "Trails" , "Essences and perfumes" .)