Dreads different snakes (6)
I believe the answer is:
adders
'snakes' is the definition.
(adder is a kind of snake)
'dreads different' is the wordplay.
'different' indicates an anagram (letters placed in a different order).
'dreads' anagrammed gives 'ADDERS'.
(Other definitions for adders that I've seen before include "Arithmetic snakes?" , "Snakes are totters" , "Re Dad's snakes" , "Mathematical reptiles" , "Sadder with snakes" .)