A couple of points in the lower bowel (5)
I believe the answer is:
colon
'bowel' is the definition.
(colon is a kind of bowel)
'a couple of points in the lower' is the wordplay.
'a couple of points' becomes 'colo' (I am not sure about this - if you are sure you should believe this answer much more).
'the lower' says to take the final letters (I've seen 'lowest' mean this (in a down clue, the bottom-most letter)).
The final letter of 'in' is 'n'.
'colo'+'n'='COLON'
Can you help me to learn more?
(Other definitions for colon that I've seen before include ": - bit of the gut" , "cash" , "almost the end of another" , "Large intestine; punctuation mark" , "Costa Rican currency" .)