One rolling up for protection from fellow corporate head: what a blunder! (8)
I believe the answer is:
hedgehog
'one rolling up for protection from fellow corporate head what a blunder' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'one rolling up for protection' is the wordplay.
'one rolling up' becomes 'hog' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'for' means one lot of letters go next to another (I've seen this in other clues).
'protection' becomes 'hedge' (hedge is a kind of protection).
'hog' after 'hedge' is 'HEDGEHOG'.
Can you help me to learn more?
(Other definitions for hedgehog that I've seen before include "Mrs Tiggy-Winkle, for example" , "Urchin" , "Porcupine" , "Woodland animal" , "Spiny creature" .)