The pharynx (6)
I believe the answer is:
throat
'the pharynx' is the definition.
(synonyms)
This is all the clue.
(Other definitions for throat that I've seen before include "A frog is a problem in this" , "Where the gullet and windpipe are located" , "Narrow entrance" , "Hot rat (anag) - body part" , "Passage from the back of the mouth" .)