Clobber, old-style (5)
I believe the answer is:
smite
'clobber old-style' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for smite that I've seen before include "Beat" , "Strike heavily" , "Strike in archaic way at times" , "Whack" , "Hit hard in olden times" .)