Navy engaging ordinary bloke (3)
I believe the answer is:
ron
'bloke' is the definition.
(man's name)
'navy engaging ordinary' is the wordplay.
'navy' becomes 'RN' (abbreviation for Royal Navy).
'engaging' indicates putting letters inside.
'ordinary' becomes 'O' (abbreviation e.g. O-Levels).
'rn' going around 'o' is 'RON'.
(Other definitions for ron that I've seen before include "--- Weasley, Harry Potter pal" , "Man" , "Boy's name (abbr)" , "L. - Hubbard, US sci-fi writer" , "Short man's name" .)