A torn stub joins at the sides (5)
I believe the answer is:
abuts
'at the sides' is the definition.
I can't judge whether this definition defines the answer.
'a torn stub joins' is the wordplay.
'torn' indicates an anagram.
'joins' is a charade indicator (letters next to each other).
'stub' is an anagram of 'buts'.
'a'+'buts'='ABUTS'
Can you help me to learn more?
(Other definitions for abuts that I've seen before include "Touches, leans on" , "Of building, is next to" , "borders" , "Lies adjacent to another" , "Ends or leans against" .)