Electrical discharge from vessel, reportedly (3)
I believe the answer is:
arc
'electrical discharge' is the definition.
(I've seen this before)
'vessel reportedly' is the wordplay.
'vessel' becomes 'ark' (ark is a kind of vessel).
'reportedly' shows a homophone (sound like).
'ark' sounds like 'ARC'.
'from' is the link.
(Other definitions for arc that I've seen before include "Curve of car" , "Half-moon" , "A curve; a discharge" , "Curved section" , "Curved part of circle" .)