Leading Tories are honourable (7)
I believe the answer is:
upright
'honourable' is the definition.
(I've seen this before)
'leading tories' is the wordplay.
'leading' becomes 'up' (similar in meaning).
'tories' becomes 'right'.
'up'+'right'='UPRIGHT'
'are' acts as a link.
(Other definitions for upright that I've seen before include "Honest (like a piano?)" , "Erect - honest" , "Honest like a vertical post" , "Vertical like rugby goal post" , "Erect - post" .)