Maybe one figures out it's poisonous (5)
I believe the answer is:
venom
'figures out it's poisonous' is the definition.
I can't judge whether this definition defines the answer.
'maybe one' is the wordplay.
I cannot quite see how this works, but
an anagram of 'one' is 'eno' which is within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for venom that I've seen before include "Poison - spite" , "acrimony" , "Poisonous fluid" , "Bitter malice" , "Poisonous secretion" .)