Let it out to get an appellation (5)
I believe the answer is:
title
'an appellation' is the definition.
(title is a kind of appellation)
'let it out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'let'+'it'='letit'
'letit' anagrammed gives 'TITLE'.
'to get' acts as a link.
(Other definitions for title that I've seen before include "Right of ownership" , "confers ownership" , "Lord, sir, doctor etc." , "Sign of nobility or name of a work" , "big role" .)