Sign of damage to box on the right (6)
I believe the answer is:
crater
'sign of damage' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'box on the right' is the wordplay.
'box' becomes 'crate' (crate is a kind of box).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the right' becomes 'r' (abbreviation).
'crate'+'r'='CRATER'
'to' is the link.
Can you help me to learn more?
(Other definitions for crater that I've seen before include "Fissure in the earth's crust" , "Bowl-shaped depression" , "Lunar surface dent" , "Moon cavity" , "Bowl-shaped cavity, in a volcano say" .)