Heading for Uni after a long goodbye (5)
I believe the answer is:
adieu
'goodbye' is the definition.
(synonyms)
'heading for uni after a long' is the wordplay.
'heading for' says to take the initial letters.
'after' says to put letters next to each other.
'long' becomes 'die' (to long for or to die for something is to crave it).
The first letter of 'uni' is 'u'.
'a'+'die'='adie'
'u' after 'adie' is 'ADIEU'.
(Other definitions for adieu that I've seen before include "Vale" , "Bye" , "Gallic goodbye" , "Goodbye, monsieur" , "All the best" .)