But it's not slow, to give trouble at certain points (5)
I believe the answer is:
snail
'but it's not slow to' is the definition.
I can't judge whether this definition defines the answer.
'trouble at certain points' is the wordplay.
'trouble' becomes 'ail' (synonyms).
'at' says to put letters next to each other (I've seen this in other clues).
'certain points' becomes 'sn' (I am not sure about the 'certain' bit.).
'ail' after 'sn' is 'SNAIL'.
'give' acts as a link.
Can you help me to learn more?
(Other definitions for snail that I've seen before include "trailer" , "Slow mover" , "Common garden mollusc" , "Slow slithery mollusc" , "dawdler" .)