Creature, early version thereof eating nothing without support (4)
I believe the answer is:
toad
'creature' is the definition.
(toad is a kind of creature)
'eating nothing without support' is the wordplay.
'eating' means one lot of letters goes inside another.
'nothing' becomes 'o' (looks like zero - 0).
'without support' becomes 'tad' (I can't justify this - if you can you should believe this answer much more).
'o' going within 'tad' is 'TOAD'.
'early version thereof' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for toad that I've seen before include "Hall proprietor (Grahame)" , "driver of reckless repute" , "Ancestral hall on River Bank" , "species of amphibian" , "Loathsome creature" .)