Jet in and out with fan whirring (8)
I believe the answer is:
fountain
'jet' is the definition.
(synonyms)
'in and out with fan whirring' is the wordplay.
I cannot really see how this works, but
'in' is present in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for fountain that I've seen before include "Spurt" , "gusher" , "Man-made water-jet" , "Ornamental water feature" , "Man-made jet of water" .)