Control signals malfunctioning if craft comes to Earth (7,6)
I believe the answer is:
traffic lights
'control signals' is the definition.
'malfunctioning if craft comes to earth' is the wordplay.
'malfunctioning' indicates anagramming the letters.
'comes to earth' becomes 'lights'.
'if'+'craft'='ifcraft'
'ifcraft' with letters rearranged gives 'traffic'.
'traffic'+'lights'='TRAFFIC LIGHTS'
(Other definitions for traffic lights that I've seen before include "Illuminated road signals" , "Road feature" .)