State of Britain boosted with a victory song (7)
I believe the answer is:
bavaria
'state of britain' is the definition.
'Bavaria' can be an answer for 'state' (Bavaria is an example). I am not certain of the 'of britain' bit.
'boosted with a victory song' is the wordplay.
'boosted' becomes 'b' (this might be a standard abbreviation which I don't know about).
'with' means one lot of letters go next to another.
'victory' becomes 'v'.
'song' becomes 'aria' (piece of music in an opera).
'b'+'a'+'v'+'aria'='BAVARIA'
Can you help me to learn more?
(Other definitions for bavaria that I've seen before include "Ludwig's place" , "site of Oktoberfest" , "mountainous state" , "Region of south Germany" , "Southern German state, famous for its beer" .)