Green’s Dictionary of Slang

(Aus.) in ironic use, a male admirer, a lover.

1885		Bulletin (Sydney) 18 Apr. 22/3: But a friend who was acquainted with the real state of affairs, gave Adonis the office, and he was seen no more about the house of Smart.
1901		Bulletin (Sydney) 5 Jan. 25/3: He is a Block Adonis, whose joy it is to hover around imported and usually theatrical stars.