What a Manx is missing (4)
I believe the answer is:
tail
'what a manx is missing' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tail that I've seen before include "part of coat" , "Animal's elongated appendage" , "Follow the caudal appendage" , "Follow; end part" , "Last, rear, part" .)