繕う (transitive, godan conjugation, hiragana つくろう, romaji tsukurou, historical hiragana つくろふ)
/tukuropu/ → /tukuroɸu/ → */tukurowu/ → /tukurou/. Compound of verb 作る (tsukuru, “to make”) in irrealis form (/tukura/) with repetitive suffix ふ (fu). The medial -ra- changed early on to -ro-.