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.
(I know that defective can be written as faulty)
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" .)