Canter around in a dream (6)
I believe the answer is:
trance
'a dream' is the definition.
(thesaurus)
'canter around' is the wordplay.
'around' is an anagram indicator.
'canter' with letters rearranged gives 'TRANCE'.
'in' acts as a link.
(Other definitions for trance that I've seen before include "state of mind" , "Deep sleeplike state" , "Canter into suspended animation" , "Reverie" , "Dream-like state" .)