Drug dispenser's charm is apt to spread (10)
I believe the answer is:
pharmacist
'drug dispenser's' is the definition.
(I've seen this before)
'charm is apt to spread' is the wordplay.
'to spread' is an anagram indicator.
'charm'+'is'+'apt'='charmisapt'
'charmisapt' is an anagram of 'PHARMACIST'.
(Other definitions for pharmacist that I've seen before include "High-street chemist" , "One who dispenses medicines" , "Drug dispenser" , "Drug dealer" , "Medicine dispenser" .)