### Clue: To sleep, say, on bed, one may lie on one's back (8)
### Answer: KNAPSACK 
 ### Explanation: Definition: one may lie on one's back
A charade of KNAP, sounding like ('say') NAP ('sleep') plus SACK ('bed'). In the surface, the two 'one's are the same; in the cryptic definition, they are not.