Last to realise university lecturer's attire is absent (9)
I believe the answer is:
elsewhere
'is absent' is the definition.
(thesaurus)
'last to realise university lecturer's attire' is the wordplay.
'last to' says to take the final letters.
'university' becomes 'lse' (London School of Economics).
'lecturer's attire' becomes 'where' (I can't explain this - if you can you should give a lot more credence to this answer).
The final letter of 'realise' is 'e'.
'e'+'lse'+'where'='ELSEWHERE'
Can you help me to learn more?
(Other definitions for elsewhere that I've seen before include "different position" , "abroad?" , "Not in this place - try another" , "away" , "In a different place" .)