Tragic middle child throttles American president (6)

I believe the answer is:

reagan

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'american president' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for reagan that I've seen before include "Former leader" , "Actor seen in old movies" , "Ronald ..., ex-president of USA" , "40th US president, d. 2004" , "leading actor, once?" .)

I've seen this clue in The Telegraph.

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