Electronic device needs dry cover removed to be functional (4)
I believe the answer is:
able
'functional' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for able that I've seen before include "Adept" , "Talented" , "Clever skilful" , "Competent as, say, sailor" , "Having the ability to do something" .)