Cathy capsized vessel (5)
I believe the answer is:
yacht
'vessel' is the definition.
(I know that yacht is a type of vessel)
'cathy capsized' is the wordplay.
'capsized' is an anagram indicator.
'cathy' is an anagram of 'YACHT'.
(Other definitions for yacht that I've seen before include "Cathy (anag.)" , "Sailing craft" , "Light, fast sailing-vessel" , "Luxury purchase" , "Sailing or motor vessel for cruising or racing" .)