Bewitched, in part, using new spell (4)
I believe the answer is:
rapt
'bewitched' is the definition.
(thesaurus)
'part using new spell' is the wordplay.
'using new spell' indicates an anagram (using a new spelling).
'part' anagrammed gives 'RAPT'.
'in' is the link.
(Other definitions for rapt that I've seen before include "Ecstatic - engrossed" , "'Transported, entranced (4)'" , "Taken up entirely" , "riveted" , "Completely absorbed" .)