Start of life is more by arrangement (6)
I believe the answer is:
embryo
'start of life' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'more by arrangement' is the wordplay.
'arrangement' is an anagram indicator.
'more'+'by'='moreby'
'moreby' with letters rearranged gives 'EMBRYO'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for embryo that I've seen before include "It's potential to grow" , "Rudimentary plant contained in seed" , "Early stage of fetus" , "Nucleus" , "Beginning of growth" .)