Jump and turn pale (4)
I believe the answer is:
leap
'jump' is the definition.
(I know that leap is a type of jump)
'turn pale' is the wordplay.
'turn' is an anagram indicator.
'pale' anagrammed gives 'LEAP'.
'and' acts as a link.
(Other definitions for leap that I've seen before include "Sudden bound" , "Jump across" , "Basket" , "Sort of year" , "vault" .)