Start a filling meal (6)
I believe the answer is:
launch
'start' is the definition.
(launching is a kind of starting)
'a filling meal' is the wordplay.
'filling' is an insertion indicator.
'meal' becomes 'lunch' (lunch is a kind of meal).
'a' placed within 'lunch' is 'LAUNCH'.
(Other definitions for launch that I've seen before include "pleasure-boat" , "Send on its course, new ship or publication" , "Propel on course, ship or rocket" , "Of ship, formally set afloat" , "Send off (a missile)" .)