Trooped out to get weapon (7)
I believe the answer is:
torpedo
'weapon' is the definition.
(weapon used at sea)
'trooped out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'trooped' with letters rearranged gives 'TORPEDO'.
'to get' is the link.
(Other definitions for torpedo that I've seen before include "Poor Ted (anag)" , "Sea-borne missile" , "[SOMETHING FISHY]" , "Missile fired from underwater submarine" , "Naval weapon" .)