Interpreter rants a lot about resistance (10)
I believe the answer is:
translator
'interpreter' is the definition.
(I know that interpreter can be written as translator)
'rants a lot about resistance' is the wordplay.
'about' is an anagram indicator.
'resistance' becomes 'r' (electronics abbreviation).
'rants'+'a'+'lot'='rantsalot'
'rantsalot' with letters rearranged gives 'translato'.
'translato'+'r'='TRANSLATOR'
(Other definitions for translator that I've seen before include "UN employee?" , "One who changes a text's language" , "One who changes the language of a text" , "One switching languages" .)