Arts graduate introducing grand American wizard (5)
I believe the answer is:
magus
'wizard' is the definition.
(I know that magus is a type of wizard)
'arts graduate introducing grand american' is the wordplay.
'arts graduate' becomes 'MA' (Master of Arts).
'introducing' suggests taking the first letters.
'american' becomes 'US' (United States).
The initial letter of 'grand' is 'g'.
'ma'+'g'+'us'='MAGUS'
(Other definitions for magus that I've seen before include "Sorcerer" , "Guru" , "Magician, wise man" , "Balthazar, Gaspar or Melchior individually" , "eg Melchior" .)