They’d ruin sea trip? (7)
I believe the answer is:
pirates
'they'd' is the definition.
I can't judge whether this definition defines the answer.
'ruin sea trip?' is the wordplay.
'ruin' indicates an anagram.
'sea'+'trip'='seatrip'
'seatrip' is an anagram of 'PIRATES'.
(Other definitions for pirates that I've seen before include "Copyright infringers" , "Sea trip (anag.)" , "Buccaneers" , "More than one brigand" , "Chatters, talks foolishly" .)