Administrators from rotten old chemical company additionally failing to finish (9)
I believe the answer is:
officials
'administrators' is the definition.
(I know this)
'rotten old chemical company additionally failing to finish' is the wordplay.
'rotten' becomes 'off' (rotten food is 'off').
'old chemical company' becomes 'ICI' (former company Imperial Chemical Industries).
'additionally' becomes 'also' (I've seen this in another clue).
'failing to finish' means to remove the last letter.
'also' with its final letter taken away is 'als'.
'off'+'ici'+'als'='OFFICIALS'
'from' acts as a link.
(Other definitions for officials that I've seen before include "Functionaries, rules administrators" , "They're in positions of authority" .)