It sounds like toothy reptile spat? (6)
I believe the answer is:
gaiter
'spat?' is the definition.
(both can mean a leg covering)
'it sounds like toothy reptile' is the wordplay.
'it sounds like' indicates a 'sounds like' (homophone) clue.
'toothy reptile' becomes 'gator' (alligator).
'gator' is a homophone of 'GAITER'.
(Other definitions for gaiter that I've seen before include "Lower leg covering" , "Legging to cover ankle and instep" , "Leg cover, spat" , "Legging or spat" , "Ankle and lower leg cover" .)