Introduce nutty dip (9)
I believe the answer is:
reduction
'dip' is the definition.
(thesaurus)
'introduce nutty' is the wordplay.
'nutty' indicates anagramming the letters.
'introduce' with letters rearranged gives 'REDUCTION'.
(Other definitions for reduction that I've seen before include "from nine to five, for example" , "Introduce by way of discount" , "cutback!" , "Decrease, diminution" , "thickened sauce?" .)