Severe abdominal pain (5)
I believe the answer is:
colic
'severe abdominal pain' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for colic that I've seen before include "gut reaction" , "Spasmodic abdominal pain" , "Intestinal infection" , "Abdominal pain from wind or obstruction" , "A severe tummy ache" .)