Clue: Train station with aspiration to become space station (7)
Answer: HOUSTON
Explanation: Definition: space station
EUSTON would be the 'train station', and pronounced 'with aspiration' (giving the H and the sound alike), it gives the Texas city, home to the Lyndon B Johnson Space Center, the flight control – ground 'station' for the USA space missions, generally rendered as just Houston in transmissions, most notably in the misquote "Houston, we've got a problem".