Confused - put on light (6)
I believe the answer is:
'confused?' is the definition.
(addling is a kind of confusing)
'put on light' is the wordplay.
'put on' becomes 'add' (I've seen this in another clue).
'light' becomes 'led' (abbreviation for light emitting diode).
(Other definitions for addled that I've seen before include "Befuddled" , "spoiled" , "Mentally confused, muddled" , "Perplexed -- rotten" , "Confused like infertile egg" .)