Crossword Genius

Man behind the mic spelling out its limits (5)

Ross

I believe the answer is:

emcee

'man behind the mic' is the definition.
(master of ceremonies)

I cannot understand how the rest of the clue works.

(Other definitions for emcee that I've seen before include "Compre" , "show director" , "Someone presenting" , "Formal host" , "I announce" .)

I've seen this clue in The Independent.
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