Doors are adjustable.
The bolts attaching the hinges to the 'A' pillar can be slackened and both hinges will move in a front/back orientation. You can use this adjustment method to move the door towards the front or the back of the car and up and down. You can also use it to rotate the door within its aperture.
Howver, unless the door has dropped at the rear or has previously been (badly) adjusted, it is somewhat unlikely that this is the cause of your problem.
Measure the panel gap between the door and the rear wing. I think it's supposed to be 4mm. If the gap is correct top to bottom it's more likely to be the wing panel as Ian says ( which is also supposed to have a 4mm panel gap to the door ).
Be very careful if you do adjust the door. The top hinge is shared with the bonnet so any adjustment you make to the top hinge has to be compensated for by moving the bonnet back or forward on it's adjustment point. I'd recommend removing the grille and slam panel during the adjustment process in case the bonnet gets jammed shut. You can at least get your hand in there then to pull the release wire manually.
And finally, if you do adjust the door, it is likely that the window will also need adjustment as well afterwards.
If the door looks OK, you're far better off just trying to adjust the wing
EDIT : As you have a spider, you also need to bear in mind the spike at the top/inside of the door at the B pillar. The block the spike goes into also has an adjustment.