Origin of headache? Errors university introduced (5)
I believe the answer is:
sinus
'origin' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'headache? errors university introduced' is the wordplay.
'headache? errors' becomes 'sins' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'university' becomes 'u' (abbreviation for university).
'introduced' means one lot of letters goes inside another.
'sins' going around 'u' is 'SINUS'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for sinus that I've seen before include "Cavity within a bone" , "Cavity linked to nose" , "Air-filled cavity in one's head" , "snotty enclosure" , "Cavity in body (connecting to nose)" .)