Genesis refuge turned up one-time serpent (5)
I believe the answer is:
krait
'serpent' is the definition.
(krait is a kind of serpent)
'genesis refuge turned up one-time' is the wordplay.
'genesis refuge' becomes 'ark' (I've seen this in another clue).
'turned up' says the letters should be written backwards.
'one' becomes 'i' (Roman numeral).
'time' becomes 't' (abbreviation).
'ark' written backwards gives 'kra'.
'kra'+'i'+'t'='KRAIT'
(Other definitions for krait that I've seen before include "Deadly snake" , "Poisonous snake" , "Out East, snake" , "Venomous Asian snake" , "Venomous snake of southeast Asia" .)