Atomic device runs, fractured at core (7)
I believe the answer is:
reactor
'atomic device' is the definition.
'reactor' can be an answer for 'device' (reactor is a kind of device). I'm not certain of the 'atomic' bit.
'runs fractured at core' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'fractured' is an anagram indicator.
'at'+'core'='atcore'
'atcore' with letters rearranged gives 'eactor'.
'r'+'eactor'='REACTOR'
Can you help me to learn more?
(Other definitions for reactor that I've seen before include "Nuclear power station core" , "chemical substance!" , "Heart of a nuclear power station" , "nuclear vessel" , "Nuclear installation" .)