Organic compound Hebe required? Not at first (7) S _ N _ O _ D
One very full of imagination (5) I _ E _ _ (thought it was IDEAL) but not so sure now
Flower left for sailors in watch once (5) T _ _ _ P (looks like TULIP, but I can't explain it)
Notion you had initially in luxury car (7) - I have THOUGHT as the anwer but can't see the luxury car