Where people finish up for assault and battery (5)
I believe the answer is:
cells
'where people finish' is the definition.
The definition suggests a singular noun but the answer is a plural noun.
'up for assault and battery' is the wordplay.
'up for assault' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'and' is a charade indicator (letters next to each other).
'battery' becomes 'cell' (I've seen this in another clue).
's' put after 'cell' is 'CELLS'.
Can you help me to learn more?
(Other definitions for cells that I've seen before include "Accommodation for prisoners" , "Dungeons" , "Small rooms" , "Mobile phone in the US" , "terrorist groups" .)