Green can high-flyer drinks after work? (7,6)

'green' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'high-flyer drinks after work?' is the wordplay.
I cannot really see how this works, but
'after' could be 'post' (prefix meaning after, eg post-war) and 'post' is found within the answer.
'work?' could be 'toil' (toil is a kind of work) and 'toil' is found in the answer.
'high-flyer' could be 'comet' (I've seen this before) and 'comet' is present in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

'can' is the link.

Can you help me to learn more?