Loot bag, bolted on top (7)
I believe the answer is:
ransack
'loot' is the definition.
(I know that loot can be written as ransack)
'bag bolted on top' is the wordplay.
'bag' becomes 'sack' (both can mean a container).
'bolted' becomes 'ran' (I've seen this in another clue).
'on top' means one lot of letters go next to another (in a down clue, some letters go above others).
'sack' put after 'ran' is 'RANSACK'.
(Other definitions for ransack that I've seen before include "Plunder or turn upside down in search" , "Rummage, rifle" , "Go through a place causing damage and stealing things" , "Plunder - rummage" , "Search (a place) thoroughly" .)