One causing buzz, Egyptian spirit loves to embrace unknown (5)
I believe the answer is:
kazoo
'one causing buzz' is the definition.
(instrument making a buzzing sound)
'egyptian spirit loves to embrace unknown' is the wordplay.
'egyptian spirit' becomes 'ka' (ancient Egyptian term for soul).
'loves' becomes 'oo' (love means 0 in tennis).
'to embrace' means one lot of letters goes inside another.
'unknown' becomes 'z' (algebra).
'ka'+'oo'='kaoo'
'kaoo' going around 'z' is 'KAZOO'.
(Other definitions for kazoo that I've seen before include "Toy wind instrument that buzzes" , "Simple musical instrument" , "Toy-like instrument into which one hums" , "Humming toy" .)