part of a rack (6)
I believe the answer is:
antler
'part of a rack' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for antler that I've seen before include "Animal's extension" , "Bony outgrowth in the deer family" , "Stag horn" , "Deer-horn" , "part of Rudolph" .)