The story
Legend attributes the term to former Irish full back and captain Ernie Crawford, who was rumoured to remark on a book read by a teammate by saying "You and your bloody Ali Khadu." Another possible origin dates from the amateur days of the game, when hard-pressed club helpers, when asked for more balls, players, games and etc., the reply was "it's all I can do". Hence alickadoo.
Etymology from Wiktionary, CC BY-SA 4.0.