New style navy (6)
I believe the answer is:
modern
'new' is the definition.
(I've seen this before)
'style navy' is the wordplay.
'style' becomes 'mode' ('mode' can be a synonym of 'style').
'navy' becomes 'rn' (abbreviation for Royal Navy).
'mode'+'rn'='MODERN'
(Other definitions for modern that I've seen before include "'Contemporary, up-to-date (6)'" , "Fashionable (like the new Tate gallery?)" , "Belonging to the present or recent times" , "The very latest available" , "Recent, up to date" .)