One imagined being unoriginal, taking year off after college (7)
I believe the answer is:
unicorn
'off after college' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'one imagined being unoriginal taking year' is the wordplay.
'one imagined being' becomes 'uni' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'unoriginal' becomes 'corny' (similar in meaning).
'taking' is a deletion indicator.
'year' becomes 'y'.
'corny' with 'y' taken out is 'corn'.
'uni'+'corn'='UNICORN'
Can you help me to learn more?
(Other definitions for unicorn that I've seen before include "Fabulous one-horned animal" , "Fabulous creature" , "Lion's traditional adversary" , "Fabulous horned animal" , "Imaginary one-horned creature" .)