How could cad harm old currency? (7)
I believe the answer is:
drachma
'currency?' is the definition.
(I have seen 'Greek currency' mean 'drachma' so perhaps 'currency' could also mean 'drachma')
'how could cad harm old' is the wordplay.
'cad harm' anagrams to 'DRACHMA'.
However, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for drachma that I've seen before include "Money no longer available" , "Old brass" , "Old Greek settler" , "Old Greek coin" , "Former Greek currency unit" .)