No longer believes, when one is further acquainted with (5,6)

'no longer believes' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'one is further acquainted with' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'is' could be 'be' and 'be' is found in the answer.
'with' could be 'w' (abbreviation) and 'w' is present in the answer.
This explanation may well be incorrect...

'when' acts as a link.

Can you help me to learn more?