Purchased (6)
'purchased' is the definition.
('buy' can be a synonym of 'purchase')
This is all the clue.
(Other definitions for bought that I've seen before include "paid for" , "Obtained" , "Puchased" , "Purchased" .)
(Other definitions for acquired that I've seen before include "Came by, obtained" , "'Got, gained (8)'" , "Got hold of" , "Obtained or procured" , "Took (on)" .)