Tusked beast's mum stood on missing first egg (8)
I believe the answer is:
mastodon
'missing first egg' 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?
'tusked beast's mum stood' is the wordplay.
I cannot quite see how this works, but
'mum' could be 'ma' (both can mean mother) and 'ma' is present in the answer.
an anagram of 'stood' is 'stodo' which is present in the answer.
A single letter 'n' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'on' is the link.
Can you help me to learn more?
(Other definitions for mastodon that I've seen before include "dead hairy beast" , "Old mammal" , "giant from the past" , "Man stood like extinct sort of elephant" , "Prehistoric creature" .)