Vehicle to take breaks in (9)
I believe the answer is:
Here is my best explanation:
'take breaks in' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'vehicle to' is the subsidiary indication.
'vehicle' becomes 'space' (space vehicle is a kind of vehicle).
'to' becomes 'ship' (I can't explain this - if you can you should give a lot more credence to this answer).
(Other definitions for spaceship that I've seen before include "Long-distance traveller", "long-distance vessel", "Orbiter", "craft going far?", "Interplanetary craft", "orbiter, perhaps", "Craft for an astronaut", "Challenger possibly", "Craft to travel outside the Earth's atmosphere" and "Transport that's out of this world".)