Seabird heading away from rear of boat (4)
I believe the answer is:
tern
'seabird' is the definition.
(I know that tern is a type of larid)
'heading away from rear of boat' is the wordplay.
'heading' is a charade indicator (letters next to each other) (some letters go in front of or head others).
'away from' becomes 'ern' (I can't explain this - if you can you should give a lot more credence to this answer).
'rear of' says to take the final letters.
The final letter of 'boat' is 't'.
'ern' after 't' is 'TERN'.
Can you help me to learn more?
(Other definitions for tern that I've seen before include "Pay rent for seabird" , "Three-masted schooner" , "Long-winged aquatic bird" , "Winger" , "Small seabird with forked tail" .)