Unit of current (3)
'unit of current' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for amp that I've seen before include "Device to up the sound of an electric guitar (abbr)" , "In short, unit for measuring electric current" , "Device making sound louder" , "A flow of one coulomb per second" , "Current; hi-fi kit" .)
'unit of current' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ampere that I've seen before include "Unit of currency" , "Solenoid inventor" , "scientist" , "Basic SI unit of electric current" , "Current measure" .)