Strong support for a weighty volume about the war (7)
I believe the answer is:
bulwark
'strong support' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'a weighty volume about the war' is the wordplay.
'a weighty volume' becomes 'bulk' (synonyms. I am not sure about the 'weighty' bit.).
'about' means one lot of letters goes inside another.
'bulk' going around 'war' is 'BULWARK'.
'for' is the link.
Can you help me to learn more?
(Other definitions for bulwark that I've seen before include "Defensive wall" , "defence" , "Buttress" , "Fortification - side of ship above deck" , "Rampart" .)