Excite, with "up" (3)
I believe the answer is:
amp
'excite with up' 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; hi-fi kit" , "Device to up the sound of an electric guitar (abbr)" , "Physics unit" , "Unit of electricity, in short" , "Current measure" .)