sql server query in stored procedure

I have this query in a stored procedure:

is it possible for me to pass a parameter to it of some sort so that it could do a slightly different piece of sql.
the difference in this case would be not including the first left join?

USE [Dictionary]
GO
/****** Object:  StoredProcedure [dbo].[usp_GetBulkDescStrings]    Script Date: 19/08/2016 17:05:35 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER PROCEDURE [dbo].[usp_GetBulkDescStrings]

AS
BEGIN
select strshort, StrShortTag, [dbo].[TblWords].ClientName, [dbo].TblVehCat.VehCategory
FROM [dbo].[TblWords] LEFT JOIN [TblWordTags] ON [TblWords].ClientCodeWordPosition = [TblWordTags].ClientCodeWordPosition LEFT JOIN [TblVehCat] ON [TblWords].ClientCode = [TblVehCat].ClientCode
WHERE [TblWordTags].ClientCodeWordPosition Is Not Null
group by strshort, StrShortTag, [dbo].[TblWords].ClientName, [dbo].TblVehCat.VehCategory
order by ClientName
END

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