Watch dog, say, beginning to splash through wee in Paris (3-3)

'watch' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'dog say beginning to splash through wee in paris' is the wordplay.
'dog say' becomes 'pet' (dog is an example).
'beginning to' suggests taking the first letters.
'through wee in paris' becomes 'it' (I can't explain this - if you can you should give a lot more credence to this answer).
The first letter of 'splash' is 's'.
'pet'+'s'+'it'='PET-SIT'

Can you help me to learn more?