CanI would prefer to go on with four letters as it was started, might give some more possibilities, but...
Cat
CarsCans
Cars
BarkBars
Bark
DankBank
SankIs that even an english word? Well, if yes
Rank
Well, thenTalkTy for enlightning meWell, then
Tank
Talk
Wall
BallFall
Ball
BeltBell
BoltBelt