Lettuce prepared for pet (6)
I believe the answer is:
cosset
'pet' is the definition.
(thesaurus)
'lettuce prepared' is the wordplay.
'lettuce' becomes 'cos' (cos lettuce is a kind of lettuce).
'prepared' becomes 'set' (I've seen this before).
'cos'+'set'='COSSET'
'for' is the link.
(Other definitions for cosset that I've seen before include "Protect overindulgently" , "Fondle" , "Nanny" , "Pamper and spoil" , "Overindulge" .)