Learning about key battleground at the eastern front (9)
I believe the answer is:
leningrad
'battleground at the eastern front' is the definition.
I can't tell whether this defines the answer.
'learning about key' is the wordplay.
'about' indicates anagramming the letters.
'key' becomes 'd' (musical key).
'learning' anagrammed gives 'leningra'.
'leningra'+'d'='LENINGRAD'
Can you help me to learn more?
(Other definitions for leningrad that I've seen before include "Former name of city" , "St Petersburg some time ago" , "St Petersburg, 1924-91" , "Soviet period name for St Petersburg" , "Name of St Petersburg from 1924 to 1991" .)