Auchinleck’s protrusion of lower jaw (4)
I believe the answer is:
chin
'lower jaw' is the definition.
(I've seen this before)
'auchinleck's protrusion' is the wordplay.
'CHIN' is hidden within the letters.
However, I'm not sure how the hidden word is indicated.
'of' is the link.
Can you help me to learn more?
(Other definitions for chin that I've seen before include "Protruding part of lower jaw" , "Punch to the face" , "narrow opening" , "Inch (anag.)" , "Facial feature" .)