His partner makes him motherless! (5)
I believe the answer is:
magog
'his partner makes him motherless' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for magog that I've seen before include "Last of two old giants" , "old giant" , "Gog and -, City of London guardian giants" , "Biblical king" , "Gog's companion" .)