Found adult tucking into meal (6)
I believe the answer is:
launch
'found' is the definition.
(to found something is to launch or establish it)
'adult tucking into meal' is the wordplay.
'adult' becomes 'a' (abbreviation).
'tucking into' means one lot of letters goes inside another.
'meal' becomes 'lunch' (lunch is a kind of meal).
'a' going into 'lunch' is 'LAUNCH'.
(Other definitions for launch that I've seen before include "Set afloat or propel into action" , "Set up - found" , "Send off (a missile)" , "Start - motor-driven boat" , "Of ship, formally set afloat" .)