Like seabird behind boat (6)
I believe the answer is:
astern
'like seabird behind boat' is the definition.
I can't tell whether this defines the answer.
'like seabird behind' is the wordplay.
'like' becomes 'as'.
'seabird' becomes 'tern' (tern is a kind of seabird).
'behind' is a charade indicator (letters next to each other).
'as'+'tern'='ASTERN'
Can you help me to learn more?
(Other definitions for astern that I've seen before include "Rearward" , "Aft" , "Towards the rear of boat" , "Backward" , "The wake is" .)