What must be paid for a liquid asset (5-4)

'asset' is the definition.
The answer and definition can be both related to property as well as being singular nouns.
Maybe they are linked in a way I don't understand?

'what must be paid for a liquid' is the wordplay.
'what must be paid' becomes 'rate' (I am not sure about this - if you are sure you should believe this answer much more).
'for' means one lot of letters go next to another (I've seen this in other clues).
'a liquid' becomes 'water' (water is a kind of liquid).
'rate' put after 'water' is 'WATER-RATE'.

Can you help me to learn more?