Snake applying pressure to indigenous North Americans (5)
I believe the answer is:
creep
'snake' is the definition.
(I've seen this before)
'pressure to indigenous north americans' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'to' means one lot of letters go next to another (I've seen this in other clues).
'indigenous north americans' becomes 'cree' (Native Americans).
'p' after 'cree' is 'CREEP'.
'applying' acts as a link.
(Other definitions for creep that I've seen before include "Inch" , "Slow motion" , "narrow passage" , "jerk?" , "wretch" .)