Company accountant leaves (4)
I believe the answer is:
coca
'leaves' is the definition.
(as in coca leaves, leaves from a coca plant)
'company accountant' is the wordplay.
'company' becomes 'co' (abbreviation).
'accountant' becomes 'ca' (abbreviation for chartered accountant).
'co'+'ca'='COCA'
(Other definitions for coca that I've seen before include "Drug-yielding shrub" , "Drug-producing plant" , "S. American drug crop" , "Narcotic shrub" , "Leaves for snow" .)