Old fogey rejected dessert and paid (7,2)

'paid' is the definition.
(to square up is to settle a bill)

'old fogey rejected dessert' is the wordplay.
'old fogey' becomes 'square' (both can mean an uncool person).
'rejected' says the letters should be written backwards.
'dessert' becomes 'pud' (short for pudding).
'pud' in reverse letter order is 'dup'.
'square'+'dup'='SQUARED UP'

'and' is the link.