Word in current usage (6)
I believe the answer is:
ampere
'word' is the definition.
The definition and answer can be both quantities as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'current usage' is the wordplay.
'current' becomes 'amp' (electricity).
'usage' becomes 'ere' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'amp'+'ere'='AMPERE'
'in' is the link.
Can you help me to learn more?
(Other definitions for ampere that I've seen before include "Solenoid inventor" , "Current analyst" , "Unit of electrical current" , "Unit of currency" , "scientist" .)