Defective (3)
'defective' is the definition.
(dud can mean faulty or defective)
This is all the clue.
(Other definitions for dud that I've seen before include "Faulty" , "Not working" , "Counterfeit article" , "Useless, doesn't work - a palindrome" , "Fake -- failure" .)
'defective' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for imperfect that I've seen before include "seconds" , "Having faults" , "Deficient" , "Faulty; tense" , "Describing continuous actions" .)
'defective' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for faulty that I've seen before include "Not working properly" , "in error" , "Flawed" , "Defective, not in good working order" , "Defective or inaccurate" .)