Shock from thunderclap palpable (5)
I believe the answer is:
appal
'shock' is the definition.
('appal' can be a synonym of 'shock')
'from thunderclap palpable' is the wordplay.
'from' indicates a hidden word.
'APPAL' is hidden within 'thunderclap palpable'.
(Other definitions for appal that I've seen before include "Scandalise" , "Disgust" , "Cause to be unpleasantly surprised" , "Fill with horror" , "Shock, horrify" .)