Bottom inch of loose end wrong, says nitpicker (4-5,4)
I believe the answer is:
fine-tooth comb
'says nitpicker' is the definition.
I can't tell whether this definition defines the answer.
'bottom inch of loose end wrong' is the wordplay.
'end' says to take the final letters.
'wrong' is an anagram indicator.
The last letter of 'loose' is 'e'.
'bottom'+'inch'+'of'+'e'='bottominchofe'
'bottominchofe' with letters rearranged gives 'FINE-TOOTH COMB'.
Can you help me to learn more?
(Other definitions for fine-tooth comb that I've seen before include "Hairdressing implement with close prongs (for careful examination?)" , "Hair groomer with narrow points" .)