Figured out what Alberto Giacometti concealed, backfired (3)
I believe the answer is:
got
'figured out' is the definition.
('get' can be a synonym of 'figure out')
'what alberto giacometti concealed backfired' is the wordplay.
'concealed' says the answer is hidden in the clue.
'backfired' says the letters should be written backwards.
'tog' can be found hidden inside 'what alberto giacometti'.
'tog' back-to-front is 'GOT'.
(Other definitions for got that I've seen before include "Landed" , "Acquired" , "came by" , "Received; understood" , "Caught" .)