Almost always in 肮脏 ('dirty; filthy'), used both literally for grime and figuratively for morally sordid dealings. Don't read it 'háng' — that older 'throat' reading is essentially never used today.
The flesh radical ⺼ (body-form, not the moon). It dates to the older 'throat' meaning of the character; in the modern 'dirty' word it survives only as the inherited radical.
Standalone 亢 supplies the sound (shifted to āng). It also points to the archaic 'throat' sense; in the everyday 'filthy' meaning it functions purely as the phonetic.
