### Clue: Send back large piece of material as evidence of work (4,5)
### Answer: TIME SHEET 
 ### Explanation: Definition: evidence of work
 **Reversal of**(… back) EMIT(to send out, as in "the chimney was seen to emit smoke") + SHEET(a large flat piece of material, metal, say).
Defn: A piece of paper recording the number of hours worked.