s, e, f, p, u are letters that make 'fess up'
fess, SS, up, Fes, Es, Fe are words within 'fess up'
1 possible definitions for 'fess up'
Under this definition, fess up is a verb and has the following properties:
make a clean breast of, own up have the same meaning as 'fess up'
'fess up' can be a type of concede, profess, confess.