Don't stint, inserting late pound in meagre bill (5,2,7)

'don't stint' is the definition.
(both can mean to spend lots of money)

'late pound in meagre bill' is the wordplay.
'late pound' becomes 'expen' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'meagre' becomes 'spare' (similar in meaning).
'bill' becomes 'nose' (I've seen this in other clues).
'spare'+'nose'='sparenose'
'expen' inserted inside 'sparenose' is 'SPARE NO EXPENSE'.

'inserting' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.

Can you help me to learn more?