Close lane, source of confusion for a special occasion (4,3)

'close lane source of confusion for a special occasion' is the definition.
I can't judge whether this defines the answer.

'source of confusion for a special occasion' is the wordplay.
'source of' suggests taking the first letters (the start - or source - of the word).
'for' is a charade indicator (letters next to each other).
'a special occasion' becomes 'oneoff' (I can't justify this - if you can you should give a lot more credence to this answer).
The first letter of 'confusion' is 'c'.
'c'+'oneoff'='CONE OFF'

Can you help me to learn more?