At late hour children turned up — to become these? (9)

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

'at late hour children turned up' is the wordplay.
'late hour' becomes 'ten' (10pm).
'children' becomes 'seed' (seed can mean one's offspring).
'turned up' says the letters should be written backwards.
'seed' backwards is 'dees'.
'at'+'ten'+'dees'='ATTENDEES'

'to' is the link.

Can you help me to learn more?