Radio star is torn, in other words (10)
I believe the answer is:
transistor
'radio' is the definition.
(I've seen this before)
'star is torn in other words' is the wordplay.
'in other words' is an anagram indicator.
'star'+'is'+'torn'='staristorn'
'staristorn' anagrammed gives 'TRANSISTOR'.
(Other definitions for transistor that I've seen before include "Electronic device" , "Electronic component" , "Radio" , "Semiconductor device" .)