衤 is the clothing radical 衣 in left-side form. It tags 褐 as a fabric and garment word, grouping it with 衫 (shirt), 袖 (sleeve), and 袍 (robe) - originally a coarse hempen cloak worn by the poor, hence the brown color the word now names.
曷 supplies the reading, drifting from hé to hè with only a tone shift. The same phonetic appears in 渴 (thirsty), 喝 (drink), and 揭 (lift), all clustered around the he syllable family with related velar onsets.
