What does it feel like? Hard, soft, squishy, etc. and does it move when you manipulate it? What do droppings look like?
If it's been this way for a year, and it's getting gradually larger, then a tumor or cyst would be suspect. If vet care is an option for you then some imaging might answer that.
If it's a pendulous crop, then I would be surprised to find a bird in good health after that much time. If the crop is not emptying completely then sour crop usually develops and the bird would likely be suffering from some weight loss, probably significant after this long. If it's in the crop then you should be able to move it up and down and around. IF it's in the crop, then after this amount of time it might require crop surgery to remove whatever the mass is. If it's a tumor/cyst then it will depend a lot on where it's growing from.