Network foundation on lough and lake, in essence (6)
I believe the answer is:
kernel
'essence' is the definition.
(I've seen this before)
'network foundation on lough and lake' is the wordplay.
'network foundation on' becomes 'k' (I am not sure about this - if you are sure you should believe this answer much more).
'lough' becomes 'erne'.
'and' says to put letters next to each other.
'lake' becomes 'l'.
'k'+'erne'+'l'='KERNEL'
'in' is the link.
Can you help me to learn more?
(Other definitions for kernel that I've seen before include "soft heart" , "Nut centre; sounds like a rank" , "Hard centre of nut" , "Core of a nut" , "Seed in hard shell" .)