Vigilant editor follows each elegy in translation (5-4)
I believe the answer is:
eagle-eyed
'vigilant' is the definition.
(thesaurus)
'editor follows each elegy in translation' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'follows' says to put letters next to each other.
'each' becomes 'ea' (abbreviation).
'in translation' is an anagram indicator (I've seen this in other clues).
'elegy' anagrammed gives 'gleey'.
'ea'+'gleey'='eagleey'
'ed' put after 'eagleey' is 'EAGLE-EYED'.
(Other definitions for eagle-eyed that I've seen before include "Having acute vision" , "Sharp-sighted" , "Keen-sighted" , "(Of someone) keeping a close watch" , "Keenly-sighted" .)