The Baggies were lying third in the Barclays Premier League but have lost their last three matches against Swansea, Stoke and Arsenal.
Head coach Clarke said: "We have to dig in. I never said it was going to be sweetness and light all season.
"I said there will come a time when results would go against us, as they have done in the last three games.
"We now need to stand up and e ready for the next challenge.
"The next seven or eight games will shape whether we have a good season or a really good season."