Treacherous type initially without support (6)
I believe the answer is:
weasel
'treacherous type' is the definition.
(weasel can mean a nasty or deceitful person)
'initially without support' is the wordplay.
'initially' indicates taking the first letters.
'support' becomes 'easel' (easel is a kind of support).
The first letter of 'without' is 'w'.
'w'+'easel'='WEASEL'
(Other definitions for weasel that I've seen before include "One deceiving" , "Small fierce animal with slender body and reddish fur" , "Stoat-like mammal - treacherous type" , "Equivocate - small animal" , "Stoat's relative" .)