Floor initially scraped with large cask (4)
I believe the answer is:
stun
'floor' is the definition.
(both can mean to shock)
'initially scraped with large cask' is the wordplay.
'initially' suggests taking the first letters.
'with' is a charade indicator (letters next to each other).
'large cask' becomes 'tun' (type of container for alcohol).
The first letter of 'scraped' is 's'.
's'+'tun'='STUN'
(Other definitions for stun that I've seen before include "what a cracker may do?" , "Anaesthetise" , "Concuss, stupefy" , "Put out for the count" , "Daze, knock senseless" .)