Assistant, unfeeling, wrote badly (6,3)
I believe the answer is:
number two
'assistant' is the definition.
(number two can mean a second in command)
'unfeeling wrote badly' is the wordplay.
'unfeeling' becomes 'numb' (synonyms).
'badly' is an anagram indicator (letters in the wrong order).
'wrote' anagrammed gives 'ertwo'.
'numb'+'ertwo'='NUMBER TWO'
(Other definitions for number two that I've seen before include "deputy" , "Dump" , "Second-in-command" , "Assistant" , "Second in command" .)