Can you use the row the card is in as a clue?

No. First entry under "Firm Rules"

Your clue must be about the meaning of the words. You can't use your clue to talk about the letters in a word or its position on the table.

I agree with a comment on another answer to keep the firm rule in place; as position clues can be used on every board, the game will become repetitive if they're allowed.

No.
From the Codenames rule book:

Your clue must be about the meaning of the words. You can't use your clue to talk about the letters in a word or its position on the table.

This rule is in place to keep the game interesting.

I would recommend keeping close to the game rules, but if the spymaster thinks they've got the perfect clue (Maybe there are two words relating to 'top' and one unrevealed card in the top row) the other spymaster can authorise a clue:

If the opposing spymaster allows it, the clue is valid. If you aren't sure, ask your opponent. (Quietly, so the others can't hear.)

The only times I've asked the other spymaster have been words that are open compound words, such as 'pet food', which represent a single concept but don't have a single word name.