Rudimentary life starts in experimental Martian base, reproducing young organisms (6)
I believe the answer is:
embryo
'rudimentary life' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'starts in experimental martian base reproducing young organisms' is the wordplay.
'starts in' says to take the initial letters.
The first letters of 'experimental martian base reproducing young organisms' is 'EMBRYO'.
Can you help me to learn more?
(Other definitions for embryo that I've seen before include "Organism in its earliest stages of development" , "Stage in development of unborn child" , "Early stage of baby, etc" , "Sometimes the result of an accident" , "Unborn offspring in the process of development" .)