Sorry being a pain..
would the statement look like this where the tag_name="CUST_RID
INSERT INTO @TEMPTABLE(TAG_NAME,TAG_DATA)
SELECT TAG_NAME = 'CUST_RID',
TAG_DATA =
( SELECT TOP 1 CLIENT_IDENTIFIER
FROM CLIENT_TO_CLIENT_IDENTIFIER_COLLECTION (NOLOCK)
INNER JOIN dbo.CLIENT_IDENTIFIER (NOLOCK) on CLIENT_IDENTIFIER.OID...