Boom and bust leaving business with an austerity champion (7)
I believe the answer is:
spartan
'austerity champion' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'boom and bust leaving business with an' is the wordplay.
'boom' becomes 'spar' (I've seen this in another clue).
'and' is a charade indicator (letters next to each other).
'bust leaving business' becomes 't' (I am not sure about this - if you are sure you should believe this answer much more).
'with' means one lot of letters go next to another.
'spar'+'t'+'an'='SPARTAN'
Can you help me to learn more?
(Other definitions for spartan that I've seen before include "Without comforts" , "Indifferent to luxury" , "Austere, lacking comfort" , "austere old Greek" , "Frugal" .)