Order zero fuss (3)
I believe the answer is:
ado
This could be a double definition.
'order zero' is the first definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?
'fuss' is the second definition.
(synonyms)
Can you help me to learn more?
(Other definitions for ado that I've seen before include "flapping" , "Flurry" , "'Much ... About Nothing, Shakespeare play (3)'" , "Fuss, trouble" , "agitation" .)