Cretan form of stupor (6)
I believe the answer is:
trance
'stupor' is the definition.
(I've seen this in another clue)
'cretan form' is the wordplay.
'form' is an anagram indicator (a different form of the same letters).
'cretan' with letters rearranged gives 'TRANCE'.
'of' is the link.
(Other definitions for trance that I've seen before include "Catalepsy" , "Deep sleeplike state" , "Abstracted state" , "Nectar (anag)" , "Sleep-like state experienced in canter" .)