Stretch that once had a dead end (4,8)

I believe the answer is:

life sentence

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'stretch that once had a dead end' is the definition.
The definition suggests a singular noun which matches the answer.

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(Other definitions for life sentence that I've seen before include "short extract from American magazine" , "Long prison stay" , "Long prison stretch" , "Long-term punishment" , "Long punishment" .)

I've seen this clue in The Globe and Mail.

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