Dot (5)
'dot' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for speck that I've seen before include "smoked ham" , "Tiny spot" , "Bit of dust" , "Small mark" , "Italian ham" .)
(Other definitions for polka that I've seen before include "Take rapid steps" , "a merry dance?" , "Bohemian dance with three steps and a hop" , "Dance in fast time with three steps and a hop" , "Lively dance, originally from Bohemia" .)