Papal letter (10)
I believe the answer is:
encyclical
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">papal letter</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for encyclical that I've seen before include "Pope's letter" , "Papal letter" , "measure being regularly repeated" , "I'm dispatched to see" , "letter from Vatican" .)