Storm tracker (5)
I believe the answer is:
radar
'storm tracker' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for radar that I've seen before include "Range-finding and detection system" , "Technique using beam" , "Locator that uses a microwave echo" , "System for detecting things using radio waves" , "Method of detection" .)