neck, collar, lapel
衿 centers on the area around the neck of a garment: the collar, lapel, or neckline itself.
衿 combines 衤 (clothing) with 今, which likely contributes the sound. The character refers to the collar or neck area of a garment.
The clothing radical 衤 on the left and 今 on the right suggest the part of a garment that frames the face: the collar or neckline.
For キン, imagine a king's royal collar: king -> キン, and the 衤 (clothing) part shows it's a garment neckline.