### Clue: This plan again upset prison guard (6)
### Answer: REDRAW 
 ### Explanation: Definition: This plan again
 **Reversal of**(upset) WARDER(a prison guard).
Answer: To draw up, say, a plan again (or differently). I'm unable to reconcile the verb answer with the defn. "Plan again" (verb) would be grammatically compatible with the answer, in which case "This" is superfluous. Or even "This plan"="Redraw plan", but "again" is then superfluous.