Clue: Worrying down pork pies before an all-night feast (5,5)
Answer: LYING AWAKE
Explanation: Definition: Worrying
A charade of LYING ('down pork pies'? Apart from the grammatical disparity, I would not have said that lies are downed – more like brought up) plus A WAKE ('an all-night feast' Perhaps originally – and etymologically – an all~~-light~~-night affair).