Score right inside grotto (5)
I believe the answer is:
carve
'score' is the definition.
(thesaurus)
'right inside grotto' is the wordplay.
'right' becomes 'r' (common abbreviation).
'inside' is an insertion indicator.
'grotto' becomes 'cave' (I've seen this before).
'r' going inside 'cave' is 'CARVE'.
(Other definitions for carve that I've seen before include "Cut (cooked meat)" , "Cut meat into slices for eating" , "fashion" , "produced by desire, with a shifting to the left" , "Slice up; sculpt" .)