Native Americans quietly, stealthily advance (5)
I believe the answer is:
creep
'stealthily advance' is the definition.
(creep can mean to move stealthily)
'native americans quietly' is the wordplay.
'native americans' becomes 'cree' (I've seen this in other clues).
'quietly' becomes 'p' (p for piano and quiet).
'cree'+'p'='CREEP'
(Other definitions for creep that I've seen before include "Move furtively" , "Move silently and secretly" , "Move stealthily or along the ground" , "Obsequious person" , "Move slowly and stealthily" .)