Worthless whichever way you see it (3)
I believe the answer is:
dud
'worthless' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for dud that I've seen before include "(Explosive) failure" , "Inoperative" , "Not working" , "'Flop, turkey (3)'" , "Useless (informal)" .)