Conservative figure (6)
I believe the answer is:
square
I believe this clue is a double definition.
'conservative' is the first definition.
(I know that square is a type of conservative)
'figure' is the second definition.
(I know this)
(Other definitions for square that I've seen before include "Eg, 4, 49 or 121" , "Regular shape - fuddy-duddy" , "Number such as 4 or 64" , "quits" , "Londoners associate with Leicester" .)