Without feeling, wrote off assistant (6,3)
I believe the answer is:
number two
'assistant' is the definition.
(number two can mean a second in command)
'without feeling wrote off' is the wordplay.
'without feeling' becomes 'numb' (I've seen this in another clue).
'off' is an anagram indicator.
'wrote' anagrammed gives 'ertwo'.
'numb'+'ertwo'='NUMBER TWO'
(Other definitions for number two that I've seen before include "Dump" , "deputy" , "vice" , "Second-in-command" , "Second in command" .)