Surface strategy over England (5)
I believe the answer is:
plane
'surface' is the definition.
(I've seen this before)
'strategy over england' is the wordplay.
'strategy' becomes 'plan' (a strategy is a plan or tactic).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'england' becomes 'E' (short for England).
'plan'+'e'='PLANE'
(Other definitions for plane that I've seen before include "Aircraft - level surface - carpenter's tool" , "Smooth" , "Tool for smoothing wood" , "This flier" , "Woodworking tool" .)