Chatter wrecked unirotational gear (7)
I believe the answer is:
ratchet
'unirotational gear' is the definition.
I can't judge whether this definition defines the answer.
'chatter wrecked' is the wordplay.
'wrecked' is an anagram indicator.
'chatter' is an anagram of 'RATCHET'.
Can you help me to learn more?
(Other definitions for ratchet that I've seen before include "Device promoting One Direction" , "this will stop revolutionary backsliding" , "One-way-motion toothed wheel" , "Chatter about notch on wheel" , "Device allowing motion in one direction only" .)