Bill and Pamela endlessly in study - in relation to their profile, I find that hard to read

I believe the answer is:

dead pan

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(Other definitions for dead pan that I've seen before include "'Poker-faced, impassive (7)'" , "Impassive, expressionless" , "Straight-faced" , "Aped Dan to become expressionless (4, 3)" , "Informally poker-faced, expressionless" .)

I've seen this clue in the Irish Times.

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