Lustre changed as a consequence (6)
I believe the answer is:
result
'a consequence' is the definition.
('result' can be a synonym of 'consequence')
'lustre changed' is the wordplay.
'changed' indicates anagramming the letters.
'lustre' anagrammed gives 'RESULT'.
'as' is the link.
(Other definitions for result that I've seen before include "Outcome of an undertaking" , "Consequence in Ulster (6)" , "Verdict" , "Ulster (anag) - outcome" , "Effect - outcome" .)