Artificial intelligence, holding degree: key to manufacturing old computers (5)
I believe the answer is:
abaci
'old computers' is the definition.
(an abacus is an ancient device for computation)
'artificial intelligence holding degree key to' is the wordplay.
'artificial intelligence' becomes 'ai' (synonyms).
'holding' means one lot of letters goes inside another.
'degree' becomes 'ba' (Bachelor of Arts).
'key to' becomes 'c' (I've seen this in other clues).
'ba'+'c'='bac'
'ai' placed around 'bac' is 'ABACI'.
'manufacturing' is the link.
(Other definitions for abaci that I've seen before include "help for summer" , "Counters" , "Counting-frames" , "These help with numbers" , "Simplistic adding machines" .)