Pastries with excessive filling where toddlers go (7)

'where toddlers go' is the definition.
(potties are used for toilet training children)

'pastries with excessive filling' is the wordplay.
'pastries' becomes 'pies' (pie is a kind of pastry).
'with excessive' becomes 'ott' (short for 'over the top'. I am not sure about the 'with' bit.).
'filling' indicates putting letters inside.
'pies' placed around 'ott' is 'POTTIES'.