Seat wrecked by sailors towards the rear (6)
I believe the answer is:
astern
'towards the rear' is the definition.
(I've seen this before)
'seat wrecked by sailors' is the wordplay.
'wrecked' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'sailors' becomes 'rn' (abbreviation for Royal Navy).
'seat' anagrammed gives 'aste'.
'aste'+'rn'='ASTERN'
(Other definitions for astern that I've seen before include "Towards the back (of a ship)" , "Toward the tail of a vessel" , "Towards a ship's rear" , "The wake is" , "Aft" .)