Catch something that keeps time, when starting late! (4)

I believe the answer is:

lock

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'catch' is the definition.
(thesaurus)

I can't explain the rest of the clue.

(Other definitions for lock that I've seen before include "Clasp" , "detail of shock?" , "Strand(s) of hair" , "Security device - bit of hair" , "Strand of hair" .)

I've seen this clue in The Hindu.

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