A key college fellow gets a peripheral (3-2)
I believe the answer is:
add-on
'a peripheral' is the definition.
I know nothing about this answer so I can't tell whether this works.
'a key college fellow' is the wordplay.
'key' becomes 'd' (I've seen this in other clues).
'college fellow' becomes 'don' (I can't justify this - if you can you should believe this answer much more).
'a'+'d'+'don'='ADD-ON'
'gets' is the link.
Can you help me to learn more?
(Other definitions for add-on that I've seen before include "Computer peripheral" , "Feature supplementing standard model" , "Extra peripheral item" , "Optional item as supplement or increment" , "Extra charge" .)