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 subsidiary indication.
'sadly' indicates anagramming the letters.
'without' indicates named letters should be taken away.
'daterepublican' with 'a' taken away is 'dterepublican'.
'dterepublican' with letters rearranged gives 'unpredictable'.
(Other definitions for unpredictable that I've seen before include "Changeable" and "Capricious".)