Focus on minor taking cannabis (9)
I believe the answer is:
spotlight
'focus' is the definition.
(thesaurus)
'minor taking cannabis' is the wordplay.
'minor' becomes 'slight' (I've seen this before**).
'taking' means one lot of letters goes inside another.
'cannabis' becomes 'pot' ('pot' can be a synonym of 'cannabis').
'slight' going around 'pot' is 'SPOTLIGHT'.
'on' acts as a link.
(Other definitions for spotlight that I've seen before include "Beam directed on small area or on stage performer" , "put in the public eye" , "exposure" , "Illumination focused on small area" , "It illuminates a small area" .)