Possible Clues:

• Sounds as if one might know this
• Less than nothing, for example, found in an oyster
• Get a vine (anag.)
• Nothing positive in camera
• Local outside for example is opposite
• Indigene has turned middle aged, no?
• Reversed image
• Like a number less than zero
• 1,000 in the phrase 'No, no a thousand times no!' is an example of a ___ number
• Expressing refusal, say, to enter local