Belgian striker Lukaku scored 17 league goals for the Baggies last season and Clarke was keen to take him back for another season, but Blues manager Jose Mourinho has said he will be part of his plans.
West Brom had originally been told Moses would not be available for them to sign, however it appears the arrivals of Willian and Samuel Eto'o to Stamford Bridge have changed Mourinho's mind.
"I exchanged text messages with Jose three or four weeks ago and he said Lukaku is definitely not going out," said Clarke.
"He said he was a big player for Chelsea this season and I think he's right.
"I believe Moses is available to come out (on loan) and he is a player we would be interested in.
"I can't say I'm confident of landing any player because time is short and I'm getting a little bit nervous."