Previously as in releasing a lenient locum? (10)
I believe the answer is:
lieutenant
'locum?' is the definition.
(thesaurus)
'previously as in releasing a lenient' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lieutenant that I've seen before include "Assistant" , "UK rank below captain" , "Substitute" , "Military rank" , "Army rank" .)