Waist measurement? Right away (5)
I believe the answer is:
girth
'waist measurement?' is the definition.
(I've seen this before)
'right away' is the wordplay.
'away' indicates an anagram (letters move away from their original places).
'right' is an anagram of 'GIRTH'.
(Other definitions for girth that I've seen before include "Measure all round" , "all the way round" , "Right (anag.)" , "A band passing under horse's belly" , "Circumferential measure" .)