Poach starter of scallops and duck (5)
I believe the answer is:
steal
'poach' is the definition.
(thesaurus)
'starter of scallops and duck' is the wordplay.
'starter of' indicates taking the first letters.
'and' says to put letters next to each other.
'duck' becomes 'teal' (teal is a kind of duck).
The first letter of 'scallops' is 's'.
's'+'teal'='STEAL'
(Other definitions for steal that I've seen before include "Take without permission" , "Take illegally" , "Lift - pocket" , "Creep" , "Plagiarise" .)