Secure in wrecked boat at first (6)
I believe the answer is:
obtain
'secure' is the definition.
('obtain' can be a synonym of 'secure')
'in wrecked boat at first' is the wordplay.
'wrecked' indicates anagramming the letters.
'at first' means one lot of letters go next to another.
'boat' anagrammed gives 'obta'.
'in' after 'obta' is 'OBTAIN'.
(Other definitions for obtain that I've seen before include "Take possession of" , "'Get, acquire (6)'" , "Get or lay hold of" , "Get or receive" , "Get one's hands on" .)