Pelf and Tidy sum

Pelf noun - Something (as pieces of stamped metal or printed paper) customarily and legally used as a medium of exchange, a measure of value, or a means of payment.

Tidy sum and pelf are semantically related. In some cases you can use "Tidy sum" instead a noun "Pelf".

Tidy sum noun - (often followed by `of') a large number or amount or extent.

Pelf and tidy sum are semantically related. Sometimes you can use "Pelf" instead a noun phrase "Tidy sum".