New seat given to sailors behind (6)
I believe the answer is:
astern
'behind' is the definition.
(I've seen this before)
'new seat given to sailors' is the wordplay.
'new' indicates anagramming the letters.
'given to' means one lot of letters go next to another.
'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 rear of a vessel" , "Backward" , "Towards back of boat" , "Behind (a boat)" , "Towards the rear of a ship" .)