Host reading out a couple of letters (5)
I believe the answer is:
emcee
'host reading out' is the definition.
'emcee' can be an answer for 'host' (emceeing is a kind of hosting). I'm not certain of the 'reading out' bit.
'a couple of letters' is the wordplay.
'a couple of letters' can mean two substitutions for 'letter'.
'letter' becomes 'em' (I've seen this in other clues).
'letter' becomes 'cee' (I've seen this before).
'em'+'cee'='EMCEE'
Can you help me to learn more?
(Other definitions for emcee that I've seen before include "anchor" , "I announce" , "Announcer" , "present" , "One presents" .)