Studio in west end of Edinburgh revamped thoroughly (6,3)
I believe the answer is:
inside out
'thoroughly' is the definition.
(I've seen this before)
'studio in west end of edinburgh revamped' is the wordplay.
'west end of' indicates taking the first letters (the leftmost letter of the word).
'revamped' indicates anagramming the letters.
The initial letter of 'edinburgh' is 'e'.
'studio'+'in'+'e'='studioine'
'studioine' is an anagram of 'INSIDE-OUT'.
(Other definitions for inside out that I've seen before include "how expert knows his trade?" , "reversal of normal" , "showing things the wrong way round" , "Thoroughly" , "comprehensively" .)