Clue: Race to arrest corrupt MEP at first on trial (10)
Answer: TEMPTATION
Explanation: Definition: tri
A charade of TEMPT, an envelope ('to arrest') of EMP, an anagram ('corrupt') of 'MEP' in TT (Tourist Trophy, 'race', which came up in yesterday's Quiptic); plus 'at' plus I ('first') plus 'on'.