Move stealthily before hard and difficult battle (8)
I believe the answer is:
edgehill
'battle' is the definition.
(I've seen this before)
'move stealthily before hard and difficult' is the wordplay.
'move stealthily' becomes 'edge' (I've seen this in another clue).
'before' is a charade indicator (letters next to each other).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'and' is a charade indicator (letters next to each other).
'difficult' becomes 'ill' (ill could historically mean difficult).
'edge'+'h'+'ill'='EDGEHILL'
(Other definitions for edgehill that I've seen before include "First battle of the Civil War, 1642" , "where battle was fought" , "Battle of the English Civil War" , "Sixteen forty two Civil War battle" , "battleground" .)