With narrowest of leads in cricket match, build hastily (3,2)

I believe the answer is:

run up

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'build hastily' is the definition.
'run up' can be an answer for 'build' (thesaurus). I am unsure of the 'hastily' bit.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for run up that I've seen before include "Quickly make, appear" , "Bowling approach" , "preparation for delivery" , "Bowler's approach" , "bowler's footsteps" .)

I've seen this clue in The Telegraph.

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