Misery at the front in an unspecified battle (5)
I believe the answer is:
somme
'battle' is the definition.
(Battle of the Somme in WW1)
'misery at the front in an unspecified' is the wordplay.
'at the front' says to take the initial letters.
'in' indicates putting letters inside.
'an unspecified' becomes 'some' (some unspecified thing).
The first letter of 'misery' is 'm'.
'm' placed into 'some' is 'SOMME'.
(Other definitions for somme that I've seen before include "French 2 down" , "bloody fight" , "1916 battleground" , "French river, scene of 1916 battles" , "River of northern France" .)