Ruth’s mother-in-law’s current grumble going north (5)
I believe the answer is:
naomi
'ruth's mother-in-law's' is the definition.
(biblical figure)
'current grumble going north' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'grumble' becomes 'moan' (I've seen this in another clue).
'going north' shows that the letters should be reversed in order.
'i'+'moan'='imoan'
'imoan' reversed gives 'NAOMI'.
(Other definitions for naomi that I've seen before include "Ruth's mother-in-law (Old Testament)" , "Girl's name, meaning "pleasant"" , "woman's name" , "OT female" , "Girl" .)