Room with it on board flying saucers, perhaps (10)

I believe the answer is:

spaceships

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'board flying saucers perhaps' is the definition.
I can't tell whether this definition defines the answer.

'room with it' is the wordplay.
'room' becomes 'space' (I've seen this before).
'with it' becomes 'ships' (I can't explain this - if you can you should believe this answer much more).
'space'+'ships'='SPACESHIPS'

'on' is the link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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