See red about a rotten rag (6)
I believe the answer is:
regard
'see' is the definition.
(synonyms)
'red about a rotten rag' is the wordplay.
'about' indicates putting letters inside.
'a rotten' indicates anagramming the letters.
'rag' anagrammed gives 'gar'.
'red' placed around 'gar' is 'REGARD'.
(Other definitions for regard that I've seen before include "Consider; attention" , "Gaze at; esteem" , "Look at; admiration" , "Consider, view" , "Attention; esteem" .)