[pritambaral]

Overflow completely overrides the effect of S-bend. There is a (pretty important) reason behind S-bends.

[RobAley]

Simply add an additional S/U bend to the overflow. Less likely to get clogged as the overflow is hopefully rarely used.

[PavlovsCat]

The overflow is only for water, right? Then a filter at the overflow entrance (or just the opening being narrow enough, two/three small holes maybe) could make positively sure the overflow bend cannot possibly get clogged.