You and I and all the endless affluence (6)
I believe the answer is:
wealth
'affluence' is the definition.
(I've seen this in another clue)
'you and i and all the endless' is the wordplay.
'you and i' becomes 'we' (we means you and I).
'and all' becomes 'al' (I can't explain this - if you can you should give a lot more credence to this answer).
'endless' means to remove the last letter.
'the' with its final letter taken off is 'th'.
'we'+'al'+'th'='WEALTH'
Can you help me to learn more?
(Other definitions for wealth that I've seen before include "An abundance of valuable possessions or money" , "Assets" , "Prosperity" , "was common under Cromwell" , "Riches, worldly goods" .)