See son with cannabis (4)
I believe the answer is:
spot
'see' is the definition.
(thesaurus)
'son with cannabis' is the wordplay.
'son' becomes 's'.
'with' is a charade indicator (letters next to each other).
'cannabis' becomes 'pot' ('pot' can be a synonym of 'cannabis').
's'+'pot'='SPOT'
(Other definitions for spot that I've seen before include "Identify" , "Lady Macbeth: ''Out, damned . . . .!''" , "Mark, dot" , "point on snooker table" , "See; eruption" .)