Conscious a King is surrounded by reverence (5)
I believe the answer is:
aware
'conscious' is the definition.
('aware' can be similar in meaning to 'conscious')
'a king is surrounded by reverence' is the wordplay.
'king' becomes 'r' (r is abbreviation for rex**).
'is surrounded by' means one lot of letters goes inside another.
'reverence' becomes 'awe' ('awe' can be a synonym of 'reverence').
'a'+'r'='ar'
'ar' going into 'awe' is 'AWARE'.
(Other definitions for aware that I've seen before include "Having knowledge (of fact)" , "Bearing in mind" , "Acquainted with or conscious of" , "Cognizant" , "Conscious or having knowledge of" .)