Cannabis is too much for her (4)
I believe the answer is:
anna
'her' is the definition.
(I've seen this before)
'cannabis is too much' is the wordplay.
'is too much' indicates the answer is hidden within the clue (only some letters needed - the rest are 'too much').
'ANNA' is hidden in the letters of 'cannabis'.
'for' is the link.
(Other definitions for anna that I've seen before include "___ Pavlova, Russian dancer, d. 1931" , "Former Indian coin, girl" , "Girl's name (palindrome)" , "Former one sixteenth of Rupee" , "Former Indian coin; girl's name" .)