Battle contributing to military prestige? (5)
I believe the answer is:
ypres
'battle' is the definition.
(I know that Ypres is a pitched battle)
'contributing to military prestige?' is the wordplay.
'contributing to' indicates a hidden word (the answer contributes to part of the clue ).
'YPRES' is hidden in the letters of 'military prestige'.
(Other definitions for ypres that I've seen before include "WW1 battle town" , "World War I battleground" , "scene of battle" , "WW1 battle site" , "Belgian World War One battle site" .)