clothing_inside applies when a character has an article of clothing inserted into an orifice, whether partially or entirely

See also:

• clothing inside - insertion of various articles of clothing, non-specific to underwear
• clothing in pussy - clothing inserted inside a character's vagina
• clothing in anus - clothing inserted inside a character's anus
• clothing in mouth - clothing inserted into a character's mouth
• underwear gag - specifically for underwear stuffed into one's mouth, but not necessarily down the throat
• through clothing
• underwear stuffing - specifically for underwear
• panty stuffing - specifically for feminine underwear