The tenet I clarified after translation (8,7)
I believe the answer is:
definite article
'the' is the definition.
'tenet i clarified after translation' is the wordplay.
'after' says to put letters next to each other.
'translation' indicates an anagram.
'tenet'+'i'+'clarified'='teneticlarified'
'teneticlarified' is an anagram of 'DEFINITE ARTICLE'.
(Other definitions for definite article that I've seen before include "Black and white feature in paper" , "Maybe the" , "In English, it's always the" , "part of speech" .)