In modern Hebrew, khal-TU-ra is a gig - a part-time job one does to supplement one's main work, say when a concert violinist does a bar mitzvah to make some extra scratch.
The word's origins lie in ancient Greece, where the word for "page" (as in rather "lowly servant", not "book") was chartes. Latin was to adopt this word, which took the form charta.
We move onto the Middle Ages, when the word chartularium, a diminutive meaning little page, came about. This medieval Latin word was used in churches for the list of people (usually donors and their family members) for whom prayers needed to be said every day, to facilitate their acceptance to heaven.
Somehow chartularium made its way into the Russian Orthodox Church in the corrupted form khaltura - and with a new meaning: the prayer that a priest says at a funeral.
Priests got paid extra for these private appearances at the homes of the deceased so. But after the Communist Revolution in 1917, which discouraged the practice of religion, Russian theatre folk commandeered the word for "moonlighting" - performances done outside the theater companies they worked for.
In the 1920s, Jewish actors making aliyah to British Mandate Palestine brought khaltura with them. The word began to gain traction among the wider public, beyond acting jargon, in the 1950s. For example, a 1953 Maariv article states: A khaltura - as is known - is an unassociated solo performance of any kind of artist, during leisure hours, in the kibbutzim, in party, organization and movement balls, or in transit camps and settlement and absorption points.
Since then, the word has become completely Hebraicized word, even spawning a irregular four-letter root Kh-L-T-R, with verbs such as khilter (did a gig) and mekhalteret (doing gigs, fem.).