Sneer causing half the side dire distress (6)
I believe the answer is:
deride
'sneer' is the definition.
(I've seen this in another clue)
'half the side dire distress' is the wordplay.
'half the' suggests halving the letters.
'distress' indicates anagramming the letters.
'side' cut in half is 'de'.
'dire' with letters rearranged gives 'ride'.
'de'+'ride'='DERIDE'
'causing' is the link.
(Other definitions for deride that I've seen before include "Poke fun at" , "Jeer, belittle" , "Laugh at or make fun of" , "Ridicule, laugh at" , "Knock" .)