Worker unexpectedly ready to embrace political party (3,8)
I believe the answer is:
day labourer
'worker' is the definition.
(day labourer is a kind of worker)
'unexpectedly ready to embrace political party' is the wordplay.
'unexpectedly' indicates anagramming the letters.
'to embrace' means one lot of letters goes inside another.
'political party' becomes 'labour' (I've seen this before).
'ready' is an anagram of 'dayer'.
'dayer' placed around 'labour' is 'DAY LABOURER'.
(Another definition for day labourer that I've seen is " Worker paid according to periods worked".)