Bowel in knots — that's drinking bender! (5)
I believe the answer is:
elbow
'drinking bender' is the definition.
'elbow' can be an answer for 'bender' (something which bends). I am not sure about the 'drinking' bit.
'bowel in knots' is the wordplay.
'in knots' indicates anagramming the letters (I've seen this in other clues).
'bowel' with letters rearranged gives 'ELBOW'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for elbow that I've seen before include "Barge" , "Reject" , "Hinged joint" , "Nudging joint?" , "push" .)