What may be widely known is hidden in one respect (4,6)
I believe the answer is:
open secret
'what may be widely known' is the definition.
I can't judge whether this definition defines the answer.
'hidden in one respect' is the wordplay.
'hidden in' is an anagram indicator.
'one'+'respect'='onerespect'
'onerespect' anagrammed gives 'OPEN SECRET'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for open secret that I've seen before include "common knowledge" , "Private matter actually known to many" , "Centre pose (anag.)" , "Generally known matter" , "Everyone knows it" .)