Is second to wear wretched sack (9)
I believe the answer is:
dismissal
'sack' is the definition.
(sacking is dismissal from one's job)
'is second to wear wretched' is the wordplay.
'second' becomes 's' (common abbreviation).
'to wear' means one lot of letters goes inside another (to wear something is to be covered up by it).
'wretched' becomes 'dismal' (I've seen this before).
'is'+'s'='iss'
'iss' put within 'dismal' is 'DISMISSAL'.
(Other definitions for dismissal that I've seen before include "removal from office" , "brush-off" , "Sacking; end of innings" , "Notice" , "job loss?" .)