Emperor's footman essentially wearing outfit wrong way round (5)
I believe the answer is:
titus
'emperor's' is the definition.
(Roman emperor)
'footman essentially wearing outfit wrong way round' is the wordplay.
'essentially' indicates the central letters.
'wearing' is an insertion indicator.
'outfit' becomes 'suit' (I've seen this in another clue).
'wrong way round' says the letters should be written backwards.
The middle of 'footman' is 't'.
't' placed within 'suit' is 'sutit'.
'sutit' in reverse letter order is 'TITUS'.
(Other definitions for titus that I've seen before include "NT book" , "A Roman emperor; a Pauline addressee" , "- Andronicus (Shak.)" , "Only part of Shakespeare play" , "identifying Philemon's neighbour" .)