Cathy's new boat (5)
I believe the answer is:
yacht
'boat' is the definition.
(yacht is a type of boat)
'cathy's new' is the wordplay.
'new' indicates an anagram.
'cathy' anagrammed gives 'YACHT'.
(Other definitions for yacht that I've seen before include "Fast sailing vessel" , "Sailing or motor vessel for cruising or racing" , "Pleasure-boat" , "Type of boat" , "Sailing boat" .)