The Baggies manager insists the Macedonian must work hard to oust Liam Ridgewell from his left-back berth if he is to secure a permanent contract with the club
The 28-year-old is available for Saturday's clash with Swansea having completed a three-match ban for spitting at Tottenham defender Kyle Walker last month.
But the Dynamo Kiev loanee's return to the starting line-up is far from certain according to Clarke, largely thanks to the impressive recent form of Liam Ridgewell.
"Goran has to step up and show he can challenge for the left-back position again because Liam has been really good since he got back in," the Scot told reporters.
"Liam's had a little chance of an extended run in the team and done well.
"I like to think all the players every week, every day are trying to impress me, but there is an end product for Goran.
"His situation won't be finalised until the end of the season and he has to keep at it, keep impressing and work every day in training.”
The former Liverpool coach went on to cite his dilemma regarding Popov as proof of the Midlands club's strength in depth.
"The type of competition we've got for the left-back position is the kind of competition you want to replicate all over the pitch," he added.
"There are two good players fighting for the same position. It focuses your mind if someone is trying to take your place and it works in reverse if you're trying to get into the team."