[1] He served in World War I from 1914 with the Light Horse and later with the Artillery in Egypt and in France but returned to Australia in September 1917 after being wounded and gassed.

He became a commercial traveller and lecturer on his return and also a prominent member of the Commercial Travellers' Club and vice-president of the Paddington-Woollahra branch of the Returned and Services League.

[2][3] In 1930, he had been a prominent opponent of the "no-license" campaign, which had attempted to prohibit alcohol sales in Victoria.

[4] In 1931, he was elected to the Australian House of Representatives as the United Australia Party member for East Sydney, defeating the sitting MP, Eddie Ward of the Lang Labor party.

Having never fully recovered from his war injuries, Clasby's health suffered from the strenuous election campaign, and he died just a month later, at age 40, before he had taken his seat in the House.