A flower with no head behind the boat (6)

I believe the answer is:

astern

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'head behind the boat' is the definition.
I can't tell whether this definition defines the answer.

'a flower with no' is the wordplay.
'a flower' becomes 'aster' (type of flower).
'with' is a charade indicator (letters next to each other).
'no' becomes 'n' (common abbreviation y/n).
'aster'+'n'='ASTERN'

Can you help me to learn more?

(Other definitions for astern that I've seen before include "Ran set (anag.)" , "Rearward" , "Behind (naut.)" , "Behind the back of a ship" , "Backward" .)

I've seen this clue in The Irish Independent.

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