Found in shack: left-handed comb (6)
I believe the answer is:
hackle
'comb' is the definition.
(hackling is a kind of combing)
'found in shack left-handed' is the wordplay.
'found in' indicates a hidden word.
'HACKLE' is hidden in the letters of 'shack left handed'.
(Other definitions for hackle that I've seen before include "Feather forming part of an angler's fly" , "Feather wound around a fishing fly" .)