Two first-half goals from Leighton Baines - one of them from the penalty spot - were enough for the Toffees at Goodison Park even though Shane Long did pull a goal back after the interval.
Asked how he felt about the game, Clarke told Sky Sports: "Disappointing. It's not been a good start to the year for us. We're scratching a little bit for performances and the results are not coming.
"We're conceding goals. And when you concede two goals in the Premier League and try to chase it to get back...
"We managed to do it against Villa but it was a little too much for us today."
Asked about the penalty on the stroke of half time, Clarke added: "I think it was critical to the shape of the game, the way the game went.
"Everton had a lot of possession first half but they didn't create an awful lot of chances. They scored a good (first) goal from their point of view but a very bad defensive goal from our point of view.
"But if we'd got the game in at 1-0 with 45 minutes to come out and have a go then we might have got something from it.
"From 2-0 to 2-1 it changes the whole complexion of the game and the whole atmosphere around the place. Obviously we're on the front foot then. We just needed a break and we didn't get it.
"Graham Dorrans' free-kick was a good one but it hit the crossbar and came out and sometimes they are the margins."
The Baggies have not won a game since Boxing Day and Clarke acknowledges that he must review his own decisions in the hope of turning things around.
"We have to work harder and I have to look at myself too," he admitted. "That's always the first port of call, you look at yourself. You look to see what you can do to help your team.
"We'll go out on the training ground and work as hard as we always do and hopefully we can put it right with a good performance and a good home win on Sunday against Tottenham."