MC is most excited about a cracking sample (11)
I believe the answer is:
toastmaster
'mc' is the definition.
(thesaurus)
'most excited about a cracking sample' is the wordplay.
I cannot quite understand how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
an anagram of 'most' is 'ostm' which is located in the remaining letters.
'a' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'is' is the link.
Can you help me to learn more?
(Other definitions for toastmaster that I've seen before include "Official at social event" , "Dinner speaker" , "Organizer of tributes" , "one announces at dinner" , "Emcee at a banquet" .)