Missile distressed poor Ted (7)
I believe the answer is:
torpedo
'missile' is the definition.
(missile from a submarine)
'distressed poor ted' is the wordplay.
'distressed' is an anagram indicator.
'poor'+'ted'='poorted'
'poorted' anagrammed gives 'TORPEDO'.
(Other definitions for torpedo that I've seen before include "Explosive missile from submarine" , "Submarine weaponry" , "ruin" , "[SOMETHING FISHY]" , "attack" .)