Revolutionary hospital on site of battle long ago (8)

I believe the answer is:

marathon

'site of battle long ago' is the definition.
(site of the ancient Battle of Marathon)

'revolutionary hospital on' is the wordplay.
'revolutionary' becomes 'marat' (French revolutionary Jean-Paul Marat).
'hospital' becomes 'h'.
'marat'+'h'+'on'='MARATHON'

(Other definitions for marathon that I've seen before include "The longest foot-race" , "Severe test of endurance" , "Long distance race" , "Race of about 26 miles" , "Race; battle" .)

I've seen this clue in The Telegraph.

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