Pound payment up front: squander and be unhappy (4,4)

'be unhappy' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'pound payment up front squander' is the wordplay.
'pound' becomes 'L' (the pound sign is based on an L).
'payment' becomes 'fee' (payment for a job).
'up front' is a charade indicator (letters next to each other).
'squander' becomes 'blue' (blue can mean to waste or squander).
'l' after 'fee' is 'feel'.
'feel'+'blue'='FEEL BLUE'

'and' acts as a link.

Can you help me to learn more?