Space - it could be germ-free (7)
I believe the answer is:
aseptic
'germ-free' is the definition.
(I've seen this before)
'space it could be' is the wordplay.
'could be' indicates anagramming the letters.
'space'+'it'='spaceit'
'spaceit' anagrammed gives 'ASEPTIC'.
(Other definitions for aseptic that I've seen before include "avoiding germs" , "Free from bacteria, surgically clean" , "ideal conditions for hospital?" , "Sterile" , "Spicate (anag.)" .)