Darren Wood of the New Inn in Newport said that while he is remaining positive, the next few months will be a big blow financially.
The pub would normally host groups of dozens throughout the festive period, when the chef prepares a Christmas menu.
But this year, while Christmas Day itself will still be busy, bookings have dried up otherwise, while the pub's capacity will be limited by social distancing rules.
Mr Wood said: "We would have tables of 20 to 30 people, they won't be coming this year.
"As far as Christmas trade goes, it's pretty much a write-off.
"I think it's going to be a very tough end to the year. You just hope there's some normality in the new year.
"We still have running costs at the pub, there are fridges and freezers, the gas is still ticking over, there are partial rents.
"We are hoping that some of the [Government] grants go towards that, it won't be enough to cover all of it.
"It does put you on the back foot. Realistically, we're probably going to have five months this year we didn't trade.
"When we have traded, only half of the pub has been open because of distancing rules, quite rightly."
He said the November lockdown will be more bearable because of the hopes that it will be lifted on December 2, and also by the "chink of light" of progress on a vaccine.
He said he has decided not to offer a takeaway service during this second lockdown to avoiding taking trade away from nearby food businesses.