Pool of money (5)
I believe the answer is:
'pool of money' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for kitty that I've seen before include "19 - diminutive name for girl or pet" , "Collection of money" , "Young domestic pet" , "One part of litter queen dropped" , "Girl's name -- pooled money" .)