It was said this would be reflected in popular opinion (4)
I believe the answer is:
oral
'it was said this' is the definition.
The definition suggests a singular noun which matches the answer. I also know that 'said' relates to this answer.
'reflected in popular opinion' is the wordplay.
'reflected' shows that the letters should be reversed in order (letters reflected back).
'in' indicates the answer is hidden within the clue.
'laro' is hidden within 'popular opinion'.
'laro' in reverse letter order is 'ORAL'.
'would be' is the link.
Can you help me to learn more?
(Other definitions for oral that I've seen before include "'Spoken, not written (4)'" , "Via the mouth" , "Of the voice" , "Related to the mouth" , "Mouth-related" .)