Magnitude of blow dealt by defeat here indeterminate? (6,7)
I believe the answer is:
little bighorn
'blow dealt by defeat here indeterminate?' is the definition.
The definition suggests a singular noun which matches the answer.
'magnitude of' is the wordplay.
I cannot really see how this works, but
'magnitude' could be 'r' (r is a kind of magnitude) and 'r' is found within the answer.
'of' could be 'o' and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for little bighorn that I've seen before include "Site of Custer's defeat" , "Custer's final battle" , "Scene of Custer's Last Stand, 1876" , "native American success" .)