Cape's lack (6)
I believe the answer is:
sleeve
'cape's lack' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sleeve that I've seen before include "Part of a shirt or jacket" , "Cover for arm and vinyl record" , "Cover for a gramophone record" , "Container for LP" , "Some wear their heart on it" .)