A call for military revolution (5,4)
I believe the answer is:
about turn
'a call' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'military revolution' is the wordplay.
'military' becomes 'about' (I can't justify this - if you can you should give a lot more credence to this answer).
'revolution' becomes 'turn' (I've seen this in another clue).
'about'+'turn'='ABOUT-TURN'
'for' is the link.
Can you help me to learn more?
(Other definitions for about turn that I've seen before include "Total change of policy" , "Major change of attitude" , "order to the troops" , "command from the sergeant major?" , "Total change of direction" .)