Veneers/inlays regularly falling out, weirdly (6)
I believe the answer is:
eerily
'weirdly' is the definition.
(I've seen this before)
'veneersinlays regularly falling out' is the wordplay.
'regularly falling out' means one should take alternating letters.
The alternate letters of 'veneersinlays' are 'EERILY'.
(Other definitions for eerily that I've seen before include "in a disturbing way" , "In strange or unearthly way" , "Spookily" , "alarmingly" , "In a strange and frightening way" .)