Person of wide learning taking old college subject in US (8)
I believe the answer is:
polymath
'person of wide learning' is the definition.
(I've seen this before)
'old college subject in us' is the wordplay.
'old college' becomes 'poly' (polytechnic).
'subject in us' becomes 'math' (I can't justify this - if you can you should believe this answer much more).
'poly'+'math'='POLYMATH'
'taking' is the link.
Can you help me to learn more?
(Other definitions for polymath that I've seen before include "Person with extensive knowledge" , "Person of wide knowledge" , "Person of wide-ranging knowledge" , "Very learned person" , "Widely-informed person" .)