Where a capital standard exists (5)
I believe the answer is:
paris
'where a capital' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'standard exists' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'exists' becomes 'is' (if something 'is', it exists).
'par'+'is'='PARIS'
Can you help me to learn more?
(Other definitions for paris that I've seen before include "where plaster comes from?" , "Old prince" , "where he got plastered?" , "French capital - Trojan prince" , "Continental capital" .)