Beaten hollow (4)
I believe the answer is:
dent
'hollow' is the definition.
(both can mean an impression or indentation)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for dent that I've seen before include "tooth (13) [FRENCH]" , "Tend to make small depression" , "Small hollow" , "Tend (anag.)" , "Hollow; tend (anagram)" .)