Almost attractive at first not before time (6,6)

I believe the answer is:

pretty nearly

I'm a little stuck... Click here to teach me more about this clue!

'almost' is the definition.
Both the definition and answer are adverbs.
Perhaps you can see a link between them that I can't see?

'attractive at first not before time' is the wordplay.
'attractive' becomes 'pretty' (pretty can mean good-looking or attractive).
'at' says to put letters next to each other.
'first not' becomes 'n' (1st letter of 'not').
'before time' becomes 'early' (I've seen this before).
'pretty'+'n'+'early'='PRETTY NEARLY'

Can you help me to learn more?

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.