Escort warship (8)
I believe the answer is:
corvette
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">escort warship</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for corvette that I've seen before include "Small warship for escorting larger vessels" , "Small naval escort vessel" , "Warship smaller than a frigate" , "Fighting ship" , "Light warship" .)