Earls running from focused beam (5)
I believe the answer is:
laser
'focused beam' is the definition.
(I've seen this in another clue)
'earls running' is the wordplay.
'running' indicates an anagram.
'earls' with letters rearranged gives 'LASER'.
'from' is the link.
(Other definitions for laser that I've seen before include "Device producing a narrow, intense beam of light" , "Optical device producing an intense beam of light" , "Beam (used in surgery)" , "Intense light generator" , "Device producing thin beam of light" .)