Acrimony of eagles encircled by cable-posts (10)
I believe the answer is:
bitterness
'acrimony' is the definition.
(I know that acrimony can be written as bitterness)
'eagles encircled by cable-posts' is the wordplay.
'eagles' becomes 'ernes' (erne is a kind of eagle).
'encircled by' indicates putting letters inside.
'cable-posts' becomes 'bitts' (I can't explain this - if you can you should give a lot more credence to this answer).
'ernes' placed within 'bitts' is 'BITTERNESS'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for bitterness that I've seen before include "Animosity" , "Acridity" , "Unrelenting resentment" , "Acerbity" , "Sharp taste" .)