The Conjuror's Grid — is it a Potter novel? (15)
I believe the answer is:
prestidigitator
'the conjuror's' is the definition.
(synonyms)
'grid is it a potter novel?' is the wordplay.
'novel?' indicates anagramming the letters (I've seen 'novel' mean this (letters in a new or novel order)).
'grid'+'is'+'it'+'a'+'potter'='gridisitapotter'
'gridisitapotter' is an anagram of 'PRESTIDIGITATOR'.
(Other definitions for prestidigitator that I've seen before include "Entertainer" , "Tricky performer" , "Illusionist" , "Conjuror" .)