Formal letter (7)
I believe the answer is:
epistle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">formal letter</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for epistle that I've seen before include "extract of the Bible" , "may read this" , "A letter - as from Apostle?" , "Apostolic letter" , "A letter from St Paul" .)