A shot of an addict's drug of choice to temporarily alleviate withdrawal symptoms. Could also happen to a normal individual when a regular habit is stopped or discouraged for a certain amount of time.
Hey look Steve, the bum at the end of the road's been craving a dope fix ever since the authorities clamped down on street dealers.
Ever since Maggie's pacifier got missing, she's resorted to sucking her toes as a dope fix.