Fast walk as a demonstration (6,5)
I believe the answer is:
hunger march
'fast walk' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'as a demonstration' is the wordplay.
'as' becomes 'hunger' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a demonstration' becomes 'march' (type of protest or demonstration).
'hunger'+'march'='HUNGER MARCH'
Can you help me to learn more?
(Other definitions for hunger march that I've seen before include "1936 Jarrow demonstration" , "movement that brings protest" .)