Funnily metamorphose in …. this? (9,5)
I believe the answer is:
pantomime horse
'this?' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'funnily metamorphose in' is the wordplay.
'funnily' is an anagram indicator.
'metamorphose'+'in'='metamorphosein'
'metamorphosein' anagrammed gives 'PANTOMIME HORSE'.
(Other definitions for pantomime horse that I've seen before include "Christmas double act" , "Christmas show character" , "Costume for two performers" .)