Most elevated dizzy heights (7)
I believe the answer is:
highest
'most elevated' is the definition.
(I've seen this before)
'dizzy heights' is the wordplay.
'dizzy' indicates an anagram.
'heights' is an anagram of 'HIGHEST'.
(Other definitions for highest that I've seen before include "Most elevated" , "Most tall" , "Above all others" , "Tallest" , "Most lofty" .)