### Clue: Toning down F1 practice session (10)
### Answer: QUALIFYING 
 ### Explanation: Definition: Toning down,F1 practice session
 Double defn: 1st: Modifying or limiting a statement or position to make it less strong or positive; and 2nd: In the sport of Formula One motor racing, a practice session prior to the actual race. I wasn't sure of the equivalence of the defn. and answer. Firstly, as a noun, the answer is the process of qualifying, though I suppose it could be loosely used for the means; and secondly, as I understand it, practice sessions are distinct from a qualifying session, with the latter, but not the former, determining the starting grid positions for the actual race. And I don't think one could or should consider any session before the actual event as practice.