Half an hour after the office has been ruined, he attends to the locks (8)
I believe the answer is:
coiffeur
'half an hour after the office has been ruined he attends to the locks' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'office has been ruined he attends to the locks' is the wordplay.
I cannot really see how this works, but
an anagram of 'office' is 'coiffe' which is present in the answer.
The remaining letters 'ur' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for coiffeur that I've seen before include "Male snipper" , "A French hairdresser" , "Skilled worker" , "Tonsorial artist" , "Male hairdresser" .)