I want to Create List Definition & List Instance under particular Sub-site.It can not been seen under site Collection.
Create your List Definition using a Web Scoped feature. Set the feature attributes to Hidden=True.
You can then activate your feature manually using PowerShell for that sub-site.
For further automation you can either staple your feature to specific templates (so it is automatically included in sites which uses a specific template) or reference it in the WebFeatures element in the Onet.xml of your custom site definition.
Accomplished with the following code in Feature Activated event receiver.
SPSite site = null; SPWeb web = null; site = properties.Feature.Parent as SPSite; web = site.AllWebs["SubSite"]; SPListTemplate temp = web.ListTemplates["ListDefinition"]; Guid newg = web.Lists.Add("ListInstance", "Description", temp); SPList newlist = web.Lists[newg]; newlist.OnQuickLaunch = true; newlist.Update();