Join together and think about abandoning heroin (4)
I believe the answer is:
knit
'join together' is the definition.
(I've seen this before)
'and think about abandoning heroin' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found within the answer.
The remaining letters 'kit' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for knit that I've seen before include "Cause to unite" , "Use needles and wool" , "needlework?" , "tie" , "Make a sweater, maybe" .)