If the processor has RD and WR lines, then yes, the processor will pulse the write line with timing as described in the data sheet as it executes the "movx @dptr,A" instruction. In addition, ALE would have been pulsed to latch the low byte of the address for the memory.
If for some reason it was necessary to operate the chip write using a clear bit instruction as you state above, you are doing it in the wrong place. You would need to set up address and data THEN pulse write low, then return it high, before any other change in address and data.