Walk quietly (6)
I believe the answer is:
tiptoe
'walk quietly' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tiptoe that I've seen before include "Walk very quietly, in song through the tulips" , "''... through the tulips'' (Tiny Tim song)" , "Keep quiet" , "Walk very lightly - musically through the tulips" , "Creep" .)