Restorative pint a beer formerly 40 % nicer (9)

'restorative' is the definition.
(I've seen this in another clue)

'pint a beer formerly 40 % nicer' is the wordplay.
I cannot really see how this works, but
'pint' could be 'pt' (abbreviation) and 'pt' is present in the answer.
'a' could be 'an' and 'an' is located in the answer.
'beer' could be 'ale' (type of beer) and 'ale' is found in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?