Meal outside a Nasa event (6)
I believe the answer is:
launch
'nasa event' is the definition.
(I've seen this in another clue)
'meal outside a' is the wordplay.
'meal' becomes 'lunch' (lunch is a kind of meal).
'outside' indicates putting letters inside (some letters go outside others).
'lunch' going around 'a' is 'LAUNCH'.
(Other definitions for launch that I've seen before include "(Send) motor-boat (into the water)" , "Initiate; a boat" , "Begin; motor boat" , "Send on its course, new ship or publication" , "Set up - found" .)