Part of the digestive system (3)
'part of the digestive system' is the definition.
('gut' is part of 'digestive system')
This is all the clue.
(Other definitions for gut that I've seen before include "corporation" , "Material for violins" , "Intestine, or the stomach" , "restricted passage" , "Intestine; narrow strait" .)
'part of the digestive system' is the definition.
('esophagus' is part of 'digestive system')
This is all the clue.