Spurs took a long time to find their attacking form. Defoe, shackled by Richard Dunne, and Peter Crouch made little real impact against Carlos Cuellar.
Niko Kranjcar was the main threat to Villa with some explosive shooting on a cold, rain-swept night at Villa Park and it was ironic that Spurs' equaliser came when the Croatian was substituted.
Following their 9-1 runaway win over Wigan the Spurs attack was surprisingly blunted by Villa's re-organised resolute defence in the first half.
Spurs attempted to begin where they left off against Wigan with Kranjcar forcing Brad Friedel to make a finger-tip save from a fierce rising drive.
But it was Villa who upped the pace with a show of sheer determination. They won a series of corners with Crouch twice clearing his lines.
In the ninth minute, however, Villa surged ahead. James Milner's corner on the right was headed goalwards by Cuellar.
His effort was blocked on the line by Benoit Assou-Ekotto but Agbonlahor was quick to spot the opportunity to force the ball into the net for his eighth goal of the season.
Spurs' response was an effort from Crouch which Cuellar cleared off the line in a spell of quality attacking play.
Agbonlahor had a good opportunity to add to his first-half tally but the England striker screwed his shot wide with Spurs' defence caught on the wrong foot.
Defoe eventually got into the match when he shot on the volley from a Kranjcar pass only to see the ever alert Friedel push his effort over the bar.
Kranjcar, easily the most dangerous Spurs player, demonstrated his potential threat to Villa early in the second half when another shot from the Croatian was finger-tipped away to safety by Friedel.
Aaron Lennon was generally well held by Luke Young and the nippy England winger had a frustrating game despite Spurs dominating the second half.
Tom Huddlestone was a tower of strength for the Londoners in midfield and he orchestrated several attacks with some astute passes to put Villa under pressure in the second period.
Villa found themselves with their backs to the wall in a desperate period when they could hardly advance out of their own half.
Defoe did get the ball into the net following a Jermaine Jenas shot but it was rightly disallowed for handling.
The equaliser eventually arrived in the 77th minute when Dawson breasted down the ball before blasting his shot past Friedel.