Dad gives the press photographers a start! (4)

I believe the answer is:

papa

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'dad' is the definition.
(I know that dad can be written as papa)

I cannot understand how the rest of the clue works.

(Other definitions for papa that I've seen before include "one after Oscar" , "The old man" , "Mama's other half?" , "Pop" , "Father; letter P" .)

I've seen this clue in the Evening Standard.

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