Bill, mascot having no clothing — saucy stuff (7)
I believe the answer is:
tabasco
'saucy stuff' is the definition.
(I know that Tabasco is saucy)
'bill mascot having no clothing' is the wordplay.
'bill' becomes 'tab' (a tab is a bill at a bar).
'having no clothing' means to look at the middle letters (letters which 'clothe' the word are removed).
The centre of 'mascot' is 'asco'.
'tab'+'asco'='TABASCO'
(Other definitions for tabasco that I've seen before include "Red pepper sauce" , "condiment?" , "Hot sauce made from capsicums" , "A hot spicy sauce" , "Hot pepper sauce" .)