Contemporary fashion and the navy (6)
I believe the answer is:
modern
'contemporary' is the definition.
(I've seen this before)
'fashion and the navy' is the wordplay.
'fashion' becomes 'mode' ('mode' can be a synonym of 'fashion').
'and' says to put letters next to each other.
'the navy' becomes 'rn' (abbreviation for Royal Navy).
'mode'+'rn'='MODERN'
(Other definitions for modern that I've seen before include "In history, the period or era since the Middle Ages" , "'Contemporary, up-to-date (6)'" , "Of the present time or current fashion" , "Present-day" , "Belonging to the present or recent times" .)