Vessel associated with a tower? (5,4)

'a tower?' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'vessel' is the wordplay.
I cannot really see how this works, but
'vessel' could be 'eboat' (I've seen this before) and 'eboat' is located in the answer.
The remaining letters 'hors' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'associated with' acts as a link.

Can you help me to learn more?