Be way out including touch of scattiness (5)
I believe the answer is:
exist
'be' is the definition.
('exist' can be a synonym of 'be')
'way out including touch of scattiness' is the wordplay.
'way out' becomes 'exit' ('exit' can be a synonym of 'way out').
'including' means one lot of letters goes inside another.
'touch of' says to take the initial letters.
The first letter of 'scattiness' is 's'.
'exit' going around 's' is 'EXIST'.
(Other definitions for exist that I've seen before include "quick!" , "Live" , "Survive" , "Be alive" , "Get a life!" .)