A less sensitive issue (6)
I believe the answer is:
number
This clue is a double definition.
'a less sensitive' is the first definition.
(numb means insensitive or unfeeling)
'issue' is the second definition.
(I know that issue can be written as number)
(Other definitions for number that I've seen before include "Part of musical" , "theme tune?" , "Vend" , "Is it sung" , "28 down, for instance" .)