This at Fukushima unstable at core? Right (7)
I believe the answer is:
reactor
'this at fukushima' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'unstable at core? right' is the wordplay.
'unstable' indicates anagramming the letters.
'right' becomes 'r' (abbreviation).
'at'+'core'='atcore'
'atcore' anagrammed gives 'reacto'.
'reacto'+'r'='REACTOR'
Can you help me to learn more?
(Other definitions for reactor that I've seen before include "Device to produce energy by nuclear fission" , "power supplier" , "See 3 Down" , "Nuclear power source" , "I swing back" .)