Fixing a system of wires and cables (7)
I believe the answer is:
rigging
'fixing' is the definition.
(rigging is a kind of fixing)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for rigging that I've seen before include "Formation of masts etc. on a vessel" , "Ship's ropes etc." , "Manipulation" , "Ropes, etc, on a sailing ship" , "Sailing ship's ropes" .)