Wrongly claim wish is fanciful (9)
I believe the answer is:
whimsical
'fanciful' is the definition.
(thesaurus)
'wrongly claim wish' is the wordplay.
'wrongly' indicates anagramming the letters (I've seen this in other clues).
'claim'+'wish'='claimwish'
'claimwish' anagrammed gives 'WHIMSICAL'.
'is' is the link.
(Other definitions for whimsical that I've seen before include "odd" , "Playfully quaint" , "Quirky" , "Quaintly fantastic" , "Fanciful, fantastical" .)