Some slimmers eat duck (7)
I believe the answer is:
immerse
'duck' is the definition.
(I know that dip is a is a more specific form of the action of duck)
'some slimmers eat' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'IMMERSE' can be found hidden inside 'slimmers eat'.
(Other definitions for immerse that I've seen before include "Absorb" , "duck" , "Plunge deep into liquid" , "Submerge in water or liquid" , "Submerge in water as once for baptism" .)