High-flying electronic equipment icon with visa difficulty (8)
I believe the answer is:
avionics
'high-flying electronic equipment' is the definition.
'icon with visa difficulty' is the wordplay.
'with' means one lot of letters go next to another.
'difficulty' indicates anagramming the letters.
'icon' put after 'visa' is 'visaicon'.
'visaicon' anagrammed gives 'AVIONICS'.
(Other definitions for avionics that I've seen before include "Science of electronic systems in aeroplanes" , "Plane's electronics" , "Science of electronic systems for aeronautics" , "bomber's electronic equipment" , "Aircraft electronics" .)