The one about footing the bill we never tire of? (8,4)
I believe the answer is:
standing joke
'footing the bill we never tire of?' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'the one' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
'one' could be 'an' (an apple is one apple) and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'about' acts as a link.
Can you help me to learn more?
(Other definitions for standing joke that I've seen before include "Regular cause of amusement" , "Regular source of amusement or ridicule" , "Constant source of amusement" , "laugh" .)