Henry VIII's stature? (6)
I believe the answer is:
height
'stature?' is the definition.
('height' can be a synonym of 'stature')
'henry viii's' is the wordplay.
'henry' becomes 'h' ('H' can be a synonym of 'henry').
'viii' becomes 'eight' ('eight' can be a synonym of 'viii').
'h'+'eight'='HEIGHT'
(Other definitions for height that I've seen before include "Stature" , "Loftiness" , "Measure it from top to bottom" , "Measurement from base to top" , "Distance above ground or sea" .)