Ipswich have conceded eight goals in their last four Championship games but are still level on points with Leicester City at the top of the league table.
They conceded two more goals against Swansea City at home over the weekend but managed to grab three points with a 3-2 win.
The Tractor Boys are still in line for automatic promotion, but Clarke insisted that they need to dip into the market in the January transfer window.
He stressed that defensive reinforcements are needed in the January window as their defence has been exposed in recent games, pointing especially to Luke Woolfenden being outpaced by Jamal Lowe.
The former Championship star believes teams will look to exploit the problems in Ipswich’s backline in the coming weeks.
Clarke said on the What The EFL Podcast: “I do think with Ipswich, their defence needs improvement.
“I think in January, they might have to invest.
“You saw for one of the goals [Luke] Woolfenden really got outpaced badly by Jamal Lowe.
“These are little things that other teams will look at and maybe prey on in the weeks to come.”
Tractor Boys boss Kieran McKenna will hope to improve his side’s defensive performances and work on a few things during the international break.
