Long, whose current contract at the Hawthorns expires at the end of the season, was on the verge of joining English Premier League newboys Hull City in the summer, but the deal ultimately fell through.
The Republic of Ireland international, 26, has hit a purple patch in recent weeks, having scored three goals in his last two league appearances against Chelsea and Aston Villa respectively.
“If Shane continues to play at the level he is right now the contract issue will sort itself out,” said Clarke.
“If he’s on that level there’s no doubt. But are you asking me if I’m selling Shane in January? No, I’m not.
“Why would I sell my best, most in-form striker? I don’t think Shane will be going anywhere in January. I haven’t considered it.
“I just want Shane to continue in this run of form. I don’t want to spend the next four weeks talking about Shane’s contract or whether he’s going to be here after January because he will be.”
Long — 15/2 to score first or last against Newcastle at St James’ Park on Saturday evening — has tallied five goals and one assist in 18 matches for both club and country this season.
Trabzonspor want Berbatov
Trabzonspor president Ibrahim Haciosmanoglu has confirmed the club’s interest in signing Fulham striker Dimitar Berbatov in January.
Berbatov, formerly of Leverkusen, Tottenham and Manchester United, has struggled to find his goal-scoring form in 2013/14.
After netting 15 goals in 32 Premier League appearances for Fulham last term, United’s all-time club record signing (£30.75 million) has found the back of the net on just one occasion in 11 league appearances this term.
As a result, the Cottagers are currently in the bottom-three with 10 points from 12 games. Only 16th-placed Norwich City (23) and bottom-of-the-table Sunderland (24) have conceded more goals than Fulham (21) in England’s top-flight.
“Bulgarian striker Dimitar Berbatov has been on our agenda,” Haciosmanoglu told Turkish newspaper Hurriyet.
“We want better and better quality and are endeavouring to add that to our squad.
“We are pleased with our team, but there are weaknesses and we will supplement with whatever we need to do.
“We have the names of a few players, but I do not want to reveal them.
“Businessman Ali Agaoglu has promised us a star.”
Berbatov has been ruled a doubt for Saturday’s clash against West Ham United, who are 15/8 to win to nil, at Upton Park.