خَيْرَ مَقْدَمٍ
Translation: A fine welcome / a good arrival!
خَيْرَ: accusative first term of an iḍāfa; in this elliptical welcome it stands in an absolute-object expression.
مَقْدَمٍ: genitive second term, meaning arrival.
This is an elliptical welcome, not a finite verb. The contextual action is understood rather than voiced.