Truly reflect Michigan trio of Republicans holding office at outset (6)
I believe the answer is:
mirror
'truly reflect' is the definition.
'michigan trio of republicans holding office at outset' is the wordplay.
'michigan' becomes 'mi' (state letters).
'trio of republicans' becomes 'rrr' (I can't justify this - if you can you should give a lot more credence to this answer).
'holding' means one lot of letters goes inside another.
'at outset' indicates taking the first letters.
The initial letter of 'office' is 'o'.
'rrr' going around 'o' is 'rror'.
'mi'+'rror'='MIRROR'
(Other definitions for mirror that I've seen before include "Reflective glass" , "Alice went through one (Carroll)" , "newspaper" , "Image reflector" , "Reflecting glass" .)