Sadly date Republican without a chance (13)
I believe the answer is:
Here is my best explanation:
'chance' is the definition.
'sadly date republican without a' is the wordplay.
'sadly' is an anagram indicator.
'without' indicates named letters should be taken away.
'daterepublican' with 'a' removed is 'dterepublican'.
'dterepublican' is an anagram of 'UNPREDICTABLE'.
(Other definitions for unpredictable that I've seen before include "erratic", "Changeable" and "Capricious".)