Treacherous type in West stand (6)
I believe the answer is:
weasel
'treacherous type' is the definition.
(I've seen this before)
'west stand' is the wordplay.
'west' becomes 'w' ('W' can be a synonym of 'west').
'stand' becomes 'easel' (easel is a kind of stand**).
'w'+'easel'='WEASEL'
'in' is the link.
(Other definitions for weasel that I've seen before include "Cowardly carnivore" , "Animal; sly person" , "These sort of words are meaningless" , "Small mammal with short legs and long body and neck" , "Small fierce animal with slender body and reddish-brown fur" .)