Is love cheat going out with a prime minister? (9)
I believe the answer is:
taoiseach
'prime minister?' is the definition.
(I've seen this before)
'is love cheat going out with a' is the wordplay.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'going out with' indicates an anagram (out can mean wrong or inaccurate).
'is'+'o'+'cheat'='isocheat'
'isocheat' anagrammed with 'a' makes 'TAOISEACH'.
(Other definitions for taoiseach that I've seen before include "I 'ate chaos (anag) - Irish Republic's prime minister" , "Leader of the government" , "Irish head of government" , "PM in Dublin" , "Western PM" .)