Throat (6)
'throat' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gullet that I've seen before include "Passage between pharynx and stomach" , "Food passage in the throat" , "Oesophagus" , "Food-passage from mouth to stomach" , "part of canal" .)
(Another definition for strep that I've seen is " bacterium".)