it is common sense that one will go short in FNO and not in stock.
But then also when this point is raised i must tell the new traders that never hold short position in stocks, untill and unless you dont have them in delivery. Otherwise it will be a short delivery. It means that you agreed to sell the shares which you dont have. In that case, Exchange will lock the amount for which totaly number of shares are sold for 5 Working days excluding Saturday and Sunday. For example you short sell shares worth 1,00,000. Exchange will lock this amount and will penalize you upto 5-8% of the total amount. On 6th day, the rest of the money will be credited back to your demat account for trading.
This is a kind of issue in which no one can help you. Happened with me once in my early days of day trading. Sharing it.
To take short position in stocks, always short futures of near, next or far month. Or Stocks can be analyzed to some extent for shorting call option or buying puts to take short position in underlying.