Getting exception while starting tomcat java.lang.NoClassDefFoundError: org/springframework/web/WebApplicationInitializer

I am getting below exception while starting tomcat –

SEVERE: Error configuring application listener of class com.citi.era.configuration.ServletConfigListner
java.lang.NoClassDefFoundError: org/springframework/web/WebApplicationInitializer

Tried clean Tomcat, clean tomcat work directory but problem was not solved.
Thanks in advance.