One's thrown, say into very musical surroundings (7)
I believe the answer is:
assegai
'musical surroundings' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'one's thrown say into' is the wordplay.
'one's thrown' becomes 'assai' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'say' becomes 'eg' (both can mean for example).
'into' is an insertion indicator.
'assai' going around 'eg' is 'ASSEGAI'.
'very' acts as a link.
Can you help me to learn more?
(Other definitions for assegai that I've seen before include "A Zulu war spear" , "Wooden spear of southern Africa" , "Spear of the Bantu-speaking people of Africa" , "A Zulu warrior's spear" , "African spear" .)