Number provided by computer’s last logic circuit (3)
I believe the answer is:
nor
'logic circuit' is the definition.
(I've seen this before)
'number provided by computer's last' is the wordplay.
'number' becomes 'no' (abbreviation for 'number').
'provided by' says to put letters next to each other.
'last' suggests the final letters.
The final letter of 'computer' is 'r'.
'no'+'r'='NOR'
(Other definitions for nor that I've seen before include "Negative word" , "Neither one ... the other" , "Neither pairing" , "And not; Norman (abbr.)" , "Link word" .)