Bury lass on front of rocket -- for such a space journey? (12)
I believe the answer is:
interstellar
'front of rocket for such a space journey?' is the definition.
I can't judge whether this definition defines the answer.
'bury lass' is the subsidiary indication.
'bury' becomes 'inter' ('inter' can be a synonym of 'bury').
'lass' becomes 'stellar' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'inter'+'stellar'='interstellar'
'on' is the link.
Can you help me to learn more?
(Other definitions for interstellar that I've seen before include "In deep space" , "Occurring between stars" , "realm of Star Trek" .)