Understand concern, not small, about public relations (9)
I believe the answer is:
interpret
'understand' is the definition.
(I know that understand can be written as interpret)
'concern not small about public relations' is the wordplay.
I cannot really understand how this works, but
'not' could be 'nt' (synonyms) and 'nt' is present in the answer.
'about' could be 're' ('re' means regarding or about) and 're' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for interpret that I've seen before include "Translate or take one's own meaning from" , "Gloss needed" , "Restate from one language into another" , "Orally translate" , "Translate, make sense of" .)