Possible Clues:

• Cézanne colleague
• Friend of Clemenceau
• Waterlily painter
• London Parliament series painter
• 'Haystacks' artist Claude
• French impressionist painter (1840-1926)
• Water lily painter Claude
• French painter (you'll need the crossing to get the second letter)
• Claude who painted "Impression, Sunrise"
• Giverny's most famous resident