New missile submarine, say, moving home? (10)

I believe the answer is:

narrowboat

'moving home?' is the definition.
(type of residence which moves down canals)

'new missile submarine say' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'missile' becomes 'arrow' (arrow is a kind of missile).
'submarine say' becomes 'boat' (submarine is a type of boat).
'n'+'arrow'+'boat'='NARROWBOAT'

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.