Old money in decline? The opposite — it brings advantage (10)
I believe the answer is:
'advantage' is the definition.
(I know that expedience is a type of advantage)
'old money in decline? the opposite it' is the wordplay.
I cannot quite see how this works, but
'old' could be 'ex' (prefix meaning former or onetime) and 'ex' is located in the answer.
'money' could be 'p' and 'p' is found within the answer.
'decline?' could be 'die' (I've seen this in other clues) and 'die' is located in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
This explanation may well be incorrect...
'brings' is the link.
(Other definitions for expedience that I've seen before include "Convenience" , "a practical solution?" .)