Metrically, one’s very rigorous (9)
I believe the answer is:
intensive
'rigorous' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
'metrically one's' is the wordplay.
I cannot quite understand how this works, but
'one's' could be 'ive' ('one has' can mean 'I have') and 'ive' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'very' acts as a link.
Can you help me to learn more?
(Other definitions for intensive that I've seen before include "Demanding" , "Concentrated" , "Very vigorous or thorough; concentrating" .)