Small quantity Duke found (6)
I believe the answer is:
traced
'found' is the definition.
(I've seen this before)
'small quantity duke' is the wordplay.
'small quantity' becomes 'trace' (I've seen this before).
'duke' becomes 'd' (abbreviation).
'trace'+'d'='TRACED'
(Other definitions for traced that I've seen before include "Copied by following the lines of a drawing" , "Outlined or tracked back" , "Red cat (anag.)" , "Located" , "Followed the tracks" .)