Transport barrels out of plant (8)
I believe the answer is:
euphoria
'transport' is the definition.
(a transport can be a feeling of intense emotion)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for euphoria that I've seen before include "Jubilation" , "Exaggerated elation?" , "Sense of wellbeing" , "Feeling of general happiness" , "A feeling of wild happiness and well-being" .)