Keep alien in bad conditions (6)
I believe the answer is:
retain
'keep' is the definition.
(I know that keep can be written as retain)
'alien in bad conditions' is the wordplay.
'alien' becomes 'et' (extra terrestrial).
'in' means one lot of letters goes inside another.
'bad conditions' becomes 'rain' (I can't explain this - if you can you should believe this answer much more).
'et' placed into 'rain' is 'RETAIN'.
Can you help me to learn more?
(Other definitions for retain that I've seen before include "Hire - keep" , "Keep in place" , "Keep, hold on to something" , "Hold on to or employ counsel" , "Hold onto" .)