Manx cat's lack (4)
I believe the answer is:
tail
'manx cat's lack' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tail that I've seen before include "Trail (behind comet)" , "Hindmost part" , "Flexible part that extends from an animal's rear" , "part of coat" , "Feebler batsmen" .)