Electronic material arranged in coils (7)
I believe the answer is:
silicon
'electronic material' is the definition.
(I've seen this before)
'arranged in coils' is the wordplay.
'arranged' is an anagram indicator.
'in'+'coils'='incoils'
'incoils' anagrammed gives 'SILICON'.
(Other definitions for silicon that I've seen before include "Element used in electronic circuits" , "Semi-conducting non-metal" , "Semiconducting element" , "Non-metallic element with atomic no. 14" , "Californian valley" .)