Lift small duck (5)
I believe the answer is:
steal
'lift' is the definition.
(thesaurus)
'small duck' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'duck' becomes 'teal' (teal is a kind of duck).
's'+'teal'='STEAL'
(Other definitions for steal that I've seen before include "bargain?" , "Take illegally" , "crib" , "pirate" , "Shoplift" .)