Observe red rag waving (6)
I believe the answer is:
regard
'observe' is the definition.
(I've seen this before)
'red rag waving' is the wordplay.
'waving' indicates an anagram (letters wave around).
'red'+'rag'='redrag'
'redrag' with letters rearranged gives 'REGARD'.
(Other definitions for regard that I've seen before include "Care" , "Consider; gaze at" , "Look at - estimation" , "Concern" , "hold in respect" .)