Circumference (5)
I believe the answer is:
girth
'circumference' is the definition.
(I know that girth is a type of circumference)
This is the entire clue.
(Other definitions for girth that I've seen before include "Measure all round" , "Size of waist perhaps" , "Circumferential measure" , "Personal circumference" , "Distance around a person's body" .)