The crossword solution for the term 'PACKS TO CAPACITY' is 'FILLS'. This means that the action of packing something to capacity is referred to as 'FILLING'. This could refer to packing a suitcase, a box, or any other container with items until it is full. It could also refer to FILLING a room with people or FILLING a stadium with spectators. In any case, the term 'fills' is used to describe the action of packing something to capacity.