Sneakiness (7)
I believe the answer is:
'sneakiness' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stealth that I've seen before include "Cautious and surreptitious action or movement" , "Cats display this" , "Slyness" , "Avoiding detection by moving carefully" , "Quiet or secret way of behaviour" .)