Finished small pastries at last after flipping flake fails to rise (10)

'flipping flake fails to rise' is the definition.
I can't tell whether this definition defines the answer.

'finished small pastries at last' is the wordplay.
'finished' becomes 'over' (over can mean finished or ended).
'small' becomes 'sleep' (I can't explain this - if you can you should believe this answer much more).
'at last' suggests the final letters.
The final letter of 'pastries' is 's'.
'over'+'sleep'+'s'='OVERSLEEPS'

'after' is the link.

Can you help me to learn more?