Scoff at extremely dire rollercoaster? (6)
I believe the answer is:
deride
'scoff at' is the definition.
(I've seen this in another clue)
'extremely dire rollercoaster?' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'rollercoaster?' becomes 'ride' (I can't explain this - if you can you should give a lot more credence to this answer).
'dire' with its centre taken out is 'de'.
'de'+'ride'='DERIDE'
Can you help me to learn more?
(Other definitions for deride that I've seen before include "Test performance" , "Ridicule, scoff at" , "Ridicule, laugh at" , "Mock, scorn" , "Express contempt for" .)