Against taking one pound, say (4)
I believe the answer is:
coin
'pound say' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'against taking one' is the wordplay.
'against' becomes 'con' (as in pros and cons, for and against).
'taking' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'con' enclosing 'i' is 'COIN'.
Can you help me to learn more?
(Other definitions for coin that I've seen before include "Metal piece of money" , "Make up" , "Metallic money" , "Metal currency" , "Invent a word or phrase - for money?" .)