Official in firm facing ruin, admitting failure (9)
I believe the answer is:
commissar
'official' is the definition.
(commissar is a kind of official)
'in firm facing ruin admitting failure' is the wordplay.
'in' is an insertion indicator.
'firm' becomes 'co' (a firm is a company).
'facing' means one lot of letters go next to another.
'ruin' becomes 'mar' (I've seen this before).
'admitting failure' becomes 'miss' (I can't justify this - if you can you should give a lot more credence to this answer).
'co'+'mar'='comar'
'comar' enclosing 'miss' is 'COMMISSAR'.
Can you help me to learn more?
(Other definitions for commissar that I've seen before include "Party official" , "Soviet official" , "USSR official" , "Communist official" .)