Was he jailed due to delay? (3)

I believe the answer is:

lag

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'to delay?' is the definition.
(lag is a kind of delay)

I don't understand how the remainder of the clue works.

(Other definitions for lag that I've seen before include "Hang back" , "Delay" , "Go too slow, fail to keep up" , "Protect from cold" , "Convict (slang)" .)

I've seen this clue in the Evening Standard.

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