As an old hand, reverse-called on a semiconductor device (7)
I believe the answer is:
gnarled
'as an old hand' is the definition.
I can't judge whether this definition defines the answer.
'reverse-called on a semiconductor device' is the wordplay.
'reverse' says the letters should be written backwards.
'called' becomes 'rang' ('ring' can be a synonym of 'call'**).
'on' is a charade indicator (letters next to each other).
'a semiconductor device' becomes 'led' (LED is an example).
'rang' reversed gives 'gnar'.
'gnar'+'led'='GNARLED'
Can you help me to learn more?
(Other definitions for gnarled that I've seen before include "Knobbly and twisted (of wood)" , "Knotty" , "Rugged" , "Knotted, twisted (tree)" , "Old, twisted, and weathered" .)