Spies what is said to be floury mix for bread (8)
I believe the answer is:
ciabatta
'for bread' is the definition.
(I've seen this before)
'spies what is' is the wordplay.
'spies' becomes 'CIA' (Central Intelligence Agency).
'what is' becomes 'batta' (I can't justify this - if you can you should believe this answer much more).
'cia'+'batta'='CIABATTA'
'said to be floury mix' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for ciabatta that I've seen before include "sandwich made with this?" , "Flattish Italian bread" , "Type of Italian bread" , "Flat Italian bread made with olive oil" , "Light flat Italian bread" .)