Answer: niggler

AnswerCrossword Clue
NIGGLERPottering person.
NIGGLERTrifler.
NIGGLEROne who carps
nigglerto criticize, esp. constantly or repeatedly, in a peevish or petty way; carp
nigglerone that niggles (to worry over petty details)
nigglerto work ineffectively; trifle
nigglerto spend too much time and effort on inconsequential details