Swap shillings and farthings? (8)
I believe the answer is:
exchange
'swap' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for exchange that I've seen before include "Convert" , "Short conversation or argument" , "place of business" , "Brief argument" , "'Swap, trade (8)'" .)