This Indus sign is a combination of the noun city and the noun wheels. It translates as city transport.
Illustrative Text Reference:
Mohenjo-daro: Seal: M-6 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 5: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Indus Script Sign Number 1387: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.