Being afraid, shaking a finger (7)
I believe the answer is:
fearing
'being afraid' is the definition.
'shaking a finger' is the wordplay.
'shaking' indicates anagramming the letters.
'a'+'finger'='afinger'
'afinger' anagrammed gives 'FEARING'.
(Other definitions for fearing that I've seen before include "Nervous" , "Dreading" , "Worried about" .)