Honourable in leading Tories?
I believe the answer is:
upright
'honourable' is the definition.
(I've seen this before)
'leading tories?' is the wordplay.
'leading' becomes 'up' ('up' can be similar in meaning to 'leading').
'tories?' becomes 'right'.
'up'+'right'='UPRIGHT'
'in' is the link.
(Other definitions for upright that I've seen before include "Honest (like a piano?)" , "Type of piano" , "Erect - post" , "Standing straight up" , "not grand" .)