Logic circuit reversing part of another one (3)
I believe the answer is:
nor
'logic circuit' is the definition.
(I've seen this before)
'reversing part of another one' is the wordplay.
'reversing' shows that the letters should be reversed in order.
'part of' indicates the answer is hidden within the clue.
'ron' is hidden within 'another one'.
'ron' in reverse letter order is 'NOR'.
(Other definitions for nor that I've seen before include "In addition, not" , "Negative conjunction" , "Neither pairing" , "Negative word" , "It's also not" .)