One of the key men provides security at the state's college hospital (9)
I believe the answer is:
locksmith
'one of the key men' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'security at the state's college hospital' is the wordplay.
'security' becomes 'lock'.
'at' says to put letters next to each other.
'the state's college' becomes 'smit' (I am not sure about this - if you are sure you should believe this answer much more).
'hospital' becomes 'h' (abbreviation for hospital on maps).
'lock'+'smit'+'h'='LOCKSMITH'
'provides' acts as a link.
Can you help me to learn more?
(Other definitions for locksmith that I've seen before include "hairdresser?" , "laughing stock" , "key figure" , "Security expert" , "opener" .)