Starts to exchange useless, redundant old currency? (4)
I believe the answer is:
euro
'currency?' is the definition.
(I've seen this before)
'starts to exchange useless redundant old' is the wordplay.
'starts to' indicates taking the first letters.
The initial letters of 'exchange useless redundant old' is 'EURO'.
(Other definitions for euro that I've seen before include "Currency of France" , "Major currency" , "Bread" , "New currency" , "Coin issued Jan first, two thousand and two" .)