Some power painter has to dismiss Monet's water (4)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

WATTeau (French painter) missing ‘eau’ (French for, Monet’s, water). I’m sure, without any evidence to support my claim, the breadth of the French language (and others) we are supposed to know has been increasing since I started these; no complaints here, just saying). The unit of power.