Rocket leaves now starter for lunch, and swell cakes provided (4-3)
I believe the answer is:
lift-off
'rocket leaves' is the definition.
The definition suggests a singular noun which matches the answer.
'starter for lunch and swell cakes provided' is the wordplay.
'starter for' suggests taking the first letters.
'and' says to put letters next to each other.
'swell' becomes 'toff' (wealthy or high-class person).
'cakes' is an insertion indicator (cake can mean to cover).
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
The first letter of 'lunch' is 'l'.
'l'+'toff'='ltoff'
'ltoff' going around 'if' is 'LIFT-OFF'.
'now' acts as a link.
Can you help me to learn more?
(Other definitions for lift-off that I've seen before include "Start of rocket's journey" , "Moment of rocket's launch" , "Launch (of rocket)" , "Instant when rocket leaves launching pad" .)