Man is laying out electricity supplies, eg (5)
I believe the answer is:
mains
'electricity supplies eg' is the definition.
'man is laying out' is the wordplay.
'laying out' is an anagram indicator.
'man'+'is'='manis'
'manis' is an anagram of 'MAINS'.
(Other definitions for mains that I've seen before include "They're located in cockpit" , "power supply" , "current public source" , "Utility network" , "Followers of those starting" .)