Sneer causing half the side dire distress (6)
I believe the answer is:
deride
'sneer' is the definition.
(I've seen this before)
'half the side dire distress' is the wordplay.
'half' suggests halving the letters.
'distress' is an anagram indicator.
'side' cut in half is 'de'.
'dire' is an anagram of 'ride'.
'de'+'ride'='DERIDE'
'causing' acts as a 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" .)