Scare rattles Dicky (7)
I believe the answer is:
startle
'scare' is the definition.
(I've seen this before)
'rattles dicky' is the wordplay.
'dicky' indicates an anagram (dicky can mean ill or non-functioning).
'rattles' anagrammed gives 'STARTLE'.
(Other definitions for startle that I've seen before include "Rock" , "Surprise with starlet" , "Cause shock to" , "Take (someone) aback" , "Take unawares with rattles" .)