Amazement about a Republican being enlightened ... (5)
I believe the answer is:
aware
'being enlightened' is the definition.
(I've seen this in another clue)
'amazement about a republican' is the wordplay.
'amazement' becomes 'awe' (awe is a kind of amazement).
'about' is an insertion indicator.
'republican' becomes 'r' (abbreviation).
'a'+'r'='ar'
'awe' placed around 'ar' is 'AWARE'.
(Other definitions for aware that I've seen before include "fly" , "Attentive" , "Acquainted with or mindful of" , "Alert, conscious of" , "Knowing (of something)" .)