Cathy upset by craft (5)
I believe the answer is:
yacht
'craft' is the definition.
(I know that yacht is a type of craft)
'cathy upset' is the wordplay.
'upset' indicates anagramming the letters.
'cathy' anagrammed gives 'YACHT'.
'by' is the link.
(Other definitions for yacht that I've seen before include "Sailboat" , "Kind of boat" , "Luxury purchase" , "Light sailing-vessel for sport" , "Light sailing vessel" .)