Nuns’ dirges tragically revealing all (10)
I believe the answer is:
undressing
'revealing all' is the definition.
(revealing all of one's body)
'nuns' dirges tragically' is the wordplay.
'tragically' indicates anagramming the letters (I've seen this in other clues).
'nuns'+'dirges'='nunsdirges'
'nunsdirges' is an anagram of 'UNDRESSING'.
(Other definitions for undressing that I've seen before include "Starting to change" , "Disrobing" .)