"Leave this plane now!" and make a good start (3,3,2,1,5)

'leave this plane now' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'make a good start' is the wordplay.
I cannot quite understand how this works, but
'make' could be 'get' (synonyms) and 'get' is present in the answer.
'a' is found in the answer.
'start' could be 'off' (I've seen this before) and 'off' is found in the answer.
This may be the basis of clue (or it may be nonsense).

'and' acts as a link.

Can you help me to learn more?