Clark grabbed the headlines on Thursday having angrily hit out at the Serbian striker's workrate and attitude during sessions last week, insisting Zigic put in "possibly the worst training session in terms of a professional footballer I have ever come across".
The Blues boss admitted he did not regret leaving Zigic out of Birmingham's matchday squad on Saturday, despite the 4-0 defeat at home to promotion-chasing Watford.
Clark always stressed there was no bust-up and that the 6ft 8in target man would be back in his plans for Tuesday should he show the desired improvement.
Speaking at the club's Wast Hills training ground today, Clark - who did not take training yesterday as he analysed video footage of Sheffield Wednesday - said: "I'll be having a chat with Nikola. He trained very well on Sunday by all accounts from the staff and what I have seen on his GPS stats.
"He has really worked harder than any player. I will have a conversation with him and we'll see where we go."
Clark, whose actions over the public handling of Zigic have been received with a mixed response from the club's supporters, added: "Hopefully he'll be involved and he'll make us win the game. But it's been a tough few days I've got to say."
Another player back with Blues is Republic of Ireland midfielder Keith Fahey, who has been on compassionate leave since mid-November to deal with family circumstances back in his homeland.
Clark is delighted to welcome back Fahey, who has been doing fitness work with local club Shamrock Rovers to maintain his levels. Clark added: "Our objective now is, without risking injury, to get him back quickly and as safely as possible.
"Whether that's two weeks, four weeks, a couple of development games incorporated into that, we can get him to the level where he can be what he is, a big influence on the team."