Nonstandard form of 片付け (かたづけ). Used colloquially or by children; considered incorrect in standard Japanese. The correct form is 片付け (かたづけ).
See also: 片付け (かたづけ)
「片つけ」 is a mistake for 「片付け」.
The child said, 'Let's tidy up,' using the nonstandard form.