Mog kept rhino? (5)
I believe the answer is:
kitty
This clue is a double definition.
'mog' is the first definition.
(both can mean a cat)
'kept rhino?' is the second definition.
(communal money ie 'rhino' kept for a purpose)
(Other definitions for kitty that I've seen before include "Pool of money - how Anne Frank addressed her diary" , "Cat; fund of money" , "Pool of bets in gambling" , "Pot of money" , "that 6 ac [CAT BURGLAR] steals?" .)