Possible Clues:

• This will make one turn puce, and that's flat
• Pierce (tyre etc)
• For this you'll need 1 across if there's no heir there, by the sound of it
• That's just enough to leave one flat
• Cause of flat needing repair?
• Tyre hole
• Cut and prune drastically to reduce inflation quickly
• Small hole, in a tyre, perhaps
• Pierce, cut, prune savagely
• Flat tyre