Separated a couple of spliffs and started to smoke (5,2)
I believe the answer is:
split up
'separated' is the definition.
(split up can mean separated or divorced)
'a couple of spliffs and started to smoke' is the wordplay.
I cannot quite see how this works, but
'started to smoke' could be 'litup' (I've seen this in another clue) and 'litup' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for split up that I've seen before include "Take apart" , "End a relationship" , "Parted company" , "Divorce" , "Part company" .)