A sample of bile, a constituent of the lower gut (5)
I believe the answer is:
'lower gut' is the definition.
The definition suggests an adjective which matches the answer.
'a sample of bile a constituent of' is the wordplay.
'a sample of' says the answer is hidden in the clue (an extract or sample of the clue).
'ILEAC' can be found hidden inside 'bile a constituent of'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for ileac that I've seen before include "Relating to the small intestine" , "Connected to digestive tract" , "concerned with part of intestine" , "an intestinal section" , "of tube in body" .)