Moving contact wrecked power wire (5)
I believe the answer is:
wiper
'moving contact' is the definition.
(type of electrical contact)
'wrecked power wire' is the wordplay.
'wrecked' is an anagram indicator.
'power' becomes 'p'.
'p'+'wire'='pwire'
'pwire' anagrammed gives 'WIPER'.
(Other definitions for wiper that I've seen before include "car accessory" , "Feature of car" , "someone drying off?" , "Window-cleaner" , "Moving electrical contact" .)