Rodent's sudden movement when dodging king snake (6)
I believe the answer is:
jerboa
'rodent's' is the definition.
(jerboa is a kind of rodent)
'sudden movement when dodging king snake' is the wordplay.
'sudden movement' becomes 'jerk' (I've seen this in another clue).
'when dodging' is a deletion indicator.
'king' becomes 'K' (chess abbreviation).
'snake' becomes 'boa' (boa constrictor, type of snake).
'jerk' with 'k' removed is 'jer'.
'jer'+'boa'='JERBOA'
(Other definitions for jerboa that I've seen before include "Mouse-like jumping rodent - ear job (anag)" , "Desert-dwelling rodent" , "Desert rodent" .)