Just

=MATCH($D$7,$A:$A,0)

should suffice.

Bob Phillips wrote:
Use conditional formatting with a formula of
=ISNUMBER(MATCH($D$7,$A:$A,0))

and select a colour for the format.

If that source sheet is a different sheet to D7, then you will need to give
the cells in column A a workbook name and refer to that in the formula.