Centre-back Clarke hasn’t featured for the Baggies ever since injuring his hamstring in the win at Blackburn on August 21.
Now, though, the Brighton loanee is fit and looks set to return to the side for Friday’s derby.
And Robertson – who made more than 600 appearances for the club between 1969 and 1986 – believes Albion look more secure at the back when the Clarke plays.
“The big positive for me is that under Valerien Ismael we look a side that is well organised,” the retired defender said. “We don’t concede many chances, we give away very little at the back.
“But I do think when Clarke plays we look even more organised.
“I think ever since he has come in he has been brilliant.
“And I’d have him in the team for Blues so long as he is fit.
“He’s a great organiser and I do think the defence hasn’t looked quite as stable while he’s been out.
“That said, though, Ismael clearly knows how to set up a team to make them very hard to break down.
“And that is key in this league because it’s a division that I don’t feel has many strong teams.
“If we are defensively strong we will keep winning games because – with the attacking quality we have got – we will always score goals.
“As long as we don’t make any silly mistakes we are good enough to win any game in this division. We just have to keep going.”
Overall, Robertson has been impressed by the start Ismael has made as Baggies boss.
“At the start of the season, I think all Albion fans would have taken being in second position after 11 games,” he continued. “The gaffer has got the team playing and winning and that’s all that matters.
“I know some fans aren’t overly happy with the style.
“But the sole aim for this season is to win promotion to the Premier League.
“If we do that it will have been a fantastic season.”