Can I apply an averaging down strategy on DBS stocks at the moment to take opportunity of the current "discounted" price if my time horizon is for a say 5years period?

FYI, the banks are on a buying spree of their shares and they are doing it on dollar cost averaging - buy more, when price is low; buy less when price is high. Maybe this is a cue you could follow.

Averaging down would suggest you keep buying on the way down (if it does go down further). Think Dollar-Cost Averaging, which is passive way to stay invested regardless of the market condition.

However, it would normally be wise to say that (Dollar-cost) averaging should not be applied to a single stock but more applicable to ETFs or unit trust.

I would also skip the part of asking why you would choose DBS stocks and how much allocation (%) DBS would be in your overall portfolio and assume you've done your due diligence.

In my opinion, 5 years seems ok to me, given that we can trust the government to swiftly act and implement appropriate measures to effectively combat and eradicate COVID-19 ASAP. I can't imagine how life would be if we were to live in current conditions for another four to five years. However, if things do take a turn for the worse in the coming months, 5 years could still be too short. Just trying to stay objective.