Snake initially makes a move, biting anything (5)
I believe the answer is:
mamba
'snake' is the definition.
(I know that Mamba is a type of elapid)
'initially makes a move biting anything' is the wordplay.
'initially' suggests taking the first letters.
'move' indicates anagramming the letters.
'biting' indicates putting letters inside (bite can mean to puncture or penetrate).
'anything' becomes 'mba' (I can't explain this - if you can you should believe this answer much more).
The first letter of 'makes' is 'm'.
'm'+'a'='ma'
'ma' with letters rearranged gives 'am'.
'am' put inside 'mba' is 'MAMBA'.
(Other definitions for mamba that I've seen before include "one venomous" , "Venomous African snake (often black)" , "Death-dealing African" , "Snake that might kill" , "serpent" .)