Alter coins? (6)
I believe the answer is:
change
I believe this is a double definition.
'alter' is the first definition.
(I know that alter is a more specific form of alter)
'coins?' is the second definition.
(change can mean coins)
(Other definitions for change that I've seen before include "Make or become different" , "Conversion" , "protean" , "Little pieces" , "Make different; coins" .)