Part of small intestine (5)
I believe the answer is:
ileum
'part of small intestine' is the definition.
(I know that ileum is part of small intestine)
This is all the clue.
(Other definitions for ileum that I've seen before include "Part of canal" , "Food processor" , "Part of digestive system" , "intestine, partly" , "Part of intestines" .)