It doesn't need manpower, as a rule (10)
I believe the answer is:
matriarchy
'it doesn't need manpower' is the definition.
The definition suggests a singular noun which matches the answer.
'a rule' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'rule' could be 'r' (abbreviation for rule) and 'r' is located in the answer.
This explanation may well be incorrect...
'as' is the link.
Can you help me to learn more?
(Other definitions for matriarchy that I've seen before include "Rule by women" , "Government" .)