Battle of Cologne ramped up (7)
I believe the answer is:
marengo
'battle' is the definition.
(I know that Marengo is a pitched battle)
'of cologne ramped up' is the wordplay.
'of' indicates a hidden word.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'ogneram' is hidden within 'cologne ramped'.
'ogneram' reversed gives 'MARENGO'.
(Other definitions for marengo that I've seen before include "vegetables and wine" , "Napoleon's horse" , "Engagement of war" , "battle fought in Italy" , "Battle of the Napoleonic Wars in Piedmont" .)