Ruler making an appearance in The Mirror (4)
I believe the answer is:
emir
'ruler' is the definition.
(historical term for a Muslim ruler)
'in the mirror' is the wordplay.
'in' says the answer is hidden in the clue.
'EMIR' can be found hidden inside 'the mirror'.
'making an appearance' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for emir that I've seen before include "Title of various Muslim rulers" , "Eastern title" , "Arab ruler" , "Arabic ruler" , "Arab prince" .)