Slav embraced by Kaiser Bill (4)
I believe the answer is:
serb
'slav' is the definition.
(I've seen this in another clue)
'embraced by kaiser bill' is the wordplay.
'embraced by' indicates the answer is hidden within the clue (surrounding letters embrace the answer).
'SERB' can be found hidden inside 'kaiser bill'.
(Other definitions for serb that I've seen before include "A European national" , "Eg, native of Belgrade" , "From Belgrade, perhaps" , "Native of the Balkans" , "Someone from Belgrade?" .)