Endowed with enthusiasm, but sacked (5)
I believe the answer is:
fired
'sacked' is the definition.
(both can mean dismissed from a job)
'endowed with enthusiasm' is the wordplay.
'endowed' becomes 'd' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'enthusiasm' becomes 'fire' (I've seen this in another clue).
'd' after 'fire' is 'FIRED'.
'but' is the link.
Can you help me to learn more?
(Other definitions for fired that I've seen before include "Discharged" , "got rid of" , "Dismissed or ignited" , "Dismissed; set off" , "Set ablaze" .)