Warning not taken up about feature of several US TV series? (6)

I believe the answer is:

tocsin

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'warning' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for tocsin that I've seen before include "One sounds an alarm" , "The sound of an alarm bell" , "Warning bell" , "alarm call" , "Alarm bell to be found in Scot" .)

I've seen this clue in The Independent.

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