Do you mean use the cooker cable to supply a shower instead of the cooker?
Then subject to jointing it satisfactorily so that it can be extended, and it following a satisfactory route if concealed, and the current carrying capacity of the cable adjusted for any installation factors, and the rating of the MCB all being OK, yes.
Better clarify what the intended shower is here. If it's one which electrically heats the water, then as above. If we're talking about just a pumped shower which takes hot water from the existing system, then it's quite possible to run it from an existing circuit.
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