Take out odd parts of both amps -- electrical units (4)
I believe the answer is:
ohms
'units' is the definition.
(ohm is a kind of unit)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ohms that I've seen before include "measures of resistance" , "Units of electrical resistance" , "Frank marking" , "Frank on official post" , "Electricity" .)