Manage commercial cleric (10)
I believe the answer is:
administer
'manage' is the definition.
(I know that administer is a type of manage)
'commercial cleric' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'cleric' becomes 'minister'.
'ad'+'minister'='ADMINISTER'
(Other definitions for administer that I've seen before include "Apply" , "Manage" , "Run" , "conduct" , "Dispense" .)