Defoe has been linked with QPR for the January market.
But Allen told talkSPORT: “Jermain has been very unfortunate. He came for back pre-season looking sharp and in good shape. But Harry has made his decisions in terms of who has been playing and the results been fantastic.
“It’s a nice problem to have, but we know the quality Jermain has. He’s a fantastic player and goalscorer and he’ll certainly play his part.”