It's an adventure, missing commercial flight (6)
I believe the answer is:
escape
'flight' is the definition.
(flight can mean an escape)
'it's an adventure missing commercial' is the wordplay.
'it's an adventure' becomes 'escapade' ('escapade' can be a synonym of 'adventure').
'missing' suggests deleting specific letters.
'commercial' becomes 'ad' (abbreviation for advertisement).
'escapade' with 'ad' removed is 'ESCAPE'.
(Other definitions for escape that I've seen before include "Elude; break free" , "Getaway" , "Gain freedom" , "Break free from confinement" , "it was great for Steve McQueen!" .)