There is Partner Account field on lead object.

Salesforce says,

DescriptionID of the partner account for the partner user that owns this lead. Available only if Partner Relationship Management is enabled OR Communities is enabled and you have partner portal licenses.

Although field says lookup,it looks like will be prepopulated when a partner user creates a lead.

Is there any way to get content(ID of account) of this field.

When i try Lead.PartnerAccount it says field doesnt exist

Does anyone have a clue?.It would be really good to get hold of this field