Score hundred inside the ground (4)
I believe the answer is:
etch
'score' is the definition.
(etch can mean to score or carve into something)
'hundred inside the ground' is the wordplay.
'hundred' becomes 'c' (Roman numeral).
'inside' means one lot of letters goes inside another.
'ground' indicates an anagram ('grind' the letters into a new form).
'the' is an anagram of 'eth'.
'c' put within 'eth' is 'ETCH'.
(Other definitions for etch that I've seen before include "Carve (design) on a surface" , "Design on metal or glass using acid" , "Inscribe" , "Eat away with acid" , "What most engravers presumably find easy to do" .)