Are flight bags small? (5)
I believe the answer is:
exist
'are' is the definition.
('they are' means 'they exist')
'flight bags small?' is the wordplay.
'flight' becomes 'exit' (flight can mean an escape or exit).
'bags' is an insertion indicator (bag can mean secures or steals).
'small?' becomes 's' (abbreviation - e.g. clothes size).
'exit' enclosing 's' is 'EXIST'.
(Other definitions for exist that I've seen before include "Get a life!" , "Have objective reality" , "Scrape by" , "quick!" , "Have being or continue living" .)