Prisoners beat leaders in the lock-up's yard night and day (10)
I believe the answer is:
constantly
'night and day' is the definition.
(thesaurus)
'prisoners beat leaders in the lock-up's yard' is the wordplay.
'prisoners' becomes 'cons'.
'beat' becomes 'tan' (I've seen this before).
'leaders in' says to take the initial letters.
'lock-up's yard' becomes 'ly' (this could be a standard abbreviation I've not previously seen).
The first letter of 'the' is 't'.
'cons'+'tan'+'t'+'ly'='CONSTANTLY'
Can you help me to learn more?
(Another definition for constantly that I've seen is " All the time".)