Fuse measure (3)
I believe the answer is:
amp
'fuse measure' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for amp that I've seen before include "Current measure" , "Sound-boosting piece of equipment (abbr)" , "In short, unit for measuring electric current" , "sound is increased by this" , "Map of electrical unit" .)