### Clue: Rival cheekily appropriates slow-witted leader's first name (8)
### Answer: VLADIMIR 
 ### Explanation: Definition: leader's first name (8)
An envelope ('appropriates') of DIM ('slow-witted') in VLAIR, an anagram ('cheekily') of 'rival'. The 'leader' would be Vladimir Ilyich Ulyanov, aka Lenin.