Of warships and admirals (5)
I believe the answer is:
naval
'of warships and admirals' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for naval that I've seen before include "Relating to warships" , "Relating to nautical defence forces" , "Relating to the Senior Service" , "Relating to marine force" , "Of seaborne forces" .)