Oscar training, sailor running (9)
I believe the answer is:
operating
'running' is the definition.
('operate' can be a synonym of 'run')
'oscar training sailor' is the wordplay.
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'training' becomes 'pe'.
'sailor' becomes 'rating' (British term for a naval enlisted man).
'o'+'pe'+'rating'='OPERATING'
(Other definitions for operating that I've seen before include "Directing or controlling, machinery say" , "Performing surgery" , "(Of machine) running" , "Cutting" , "Active" .)