Hit-man's name for the letter B! (5)
I believe the answer is:
bravo
'letter b' is the definition.
'bravo' can be an answer for 'letter' (NATO phonetic alphabet). I am not sure about the 'b' bit.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for bravo that I've seen before include "Hurrah!" , "How broadcaster might begin birthday" , "Expression of approval" , "B in radio communications" , "Cry of approval" .)