Revival to appear after switching components (6)
I believe the answer is:
upturn
'revival' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for upturn that I've seen before include "Improvement, in business say" , "economic improvement" , "Improvement in fortunes" , "Improving trend" , "Recovery" .)