Answer:

fester

Answer	Crossword Clue
FESTER	Continue to irritate, as bad feeling
FESTER	Uncle at 0001 Cemetery Lane, in '60s TV
FESTER	Rankle, as resentment

FESTER	Rankle, as bad feelings
FESTER	Rankle
FESTER	"The Addams Family" uncle
FESTER	Relative of Wednesday
FESTER	Grow embittered
FESTER	Produce progressive irritation
FESTER	Addams Family uncle
FESTER	Become an increasing source of irritation

FESTER	Rot
FESTER	Grow more and more irksome
FESTER	Putrefy
FESTER	"The Addams Family" character
FESTER	"Addams Family" uncle
FESTER	Get worse and worse
FESTER	Grow in virulence
FESTER	Get worse through neglect