Bug on a wire? (3)
I believe the answer is:
tap
'bug on a wire?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tap that I've seen before include "Obtain money from" , "Thread cutter; strike" , "Valve controlling flow - light knock" , "Flow controller; knock" , "A form of dance" .)