Small red and white rats (6)

'rats' is the definition.
The answer and definition can be both animals as well as being plural nouns.
Perhaps you can see a link between them that I don't see?

'small red and white' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'red' becomes 'ines' (I can't explain this - if you can you should give a lot more credence to this answer).
'and' means one lot of letters go next to another.
'white' becomes 'w'.
'ines' after 'w' is 'wines'.
's'+'wines'='SWINES'

Can you help me to learn more?