McDermott has recently added Stoke goalkeeper Jack Butland and England Under-21 international team-mate Connor Wickham, from Sunderland, to his squad.
Cameron Stewart (Hull City) and Jimmy Kebe (Crystal Palace) also arrived on loans until the end of the season during the January transfer window.
"We've got four loans so we could bring in one more," said McDermott.
"There's a possibility. It's something we're still looking at."
McDermott signed midfielder Luke Murphy, defenders Scott Wootton and Marius Zaliukas, plus strikers Noel Hunt and Matt Smith during the summer after succeeding Neil Warnock as manager.
"I've never said that the team wasn't mine at any point, even when I came here in April," McDermott added.
"I'll always take ownership of the team. It would be wrong not to.
"I'm part of the group and part of what we're trying to do - when we have the ups and when we have the downs."