River Test's vigour (8)
I believe the answer is:
industry
'vigour' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'river test's' is the wordplay.
'river' becomes 'indus' (Indian river).
'test' becomes 'try' (synonyms).
'indus'+'try'='INDUSTRY'
Can you help me to learn more?
(Other definitions for industry that I've seen before include "Hard work" , "Diligence" , "The manufacture or production of goods" , "Commercial, manufacturing enterprise" , "Commerce" .)