Electric current inside one cooking main (5)
I believe the answer is:
chief
'main' is the definition.
(synonyms)
'electric current inside one cooking' is the wordplay.
'electric current' becomes 'I' (physics symbol).
'inside' is an insertion indicator.
'one cooking' becomes 'chef' (someone who cooks).
'i' inserted within 'chef' is 'CHIEF'.
(Other definitions for chief that I've seen before include "Main" , "cardinal" , "Principal" , "Tribal head" , "Tribe leader" .)