Possible Clues:

• Clever, closing window a little bit
• To a small extent
• Crafty, closing window a tiny bit
• A little cunning about this, perhaps
• Not dim, admitted to knowing a bit
• To a small degree, it's tricky hiding source of illumination
• A bit, rather
• Crafty match inside to a certain extent
• A bit pale in sneaky surroundings
• To a very small degree