Eats in number one brasserie, essentially showing character of a weakling (9)

'character of a weakling' is the definition.
The definition suggests a singular noun which matches the answer.

'eats in number one brasserie essentially' is the wordplay.
'eats' becomes 'dines' (dining is a kind of eating).
'in' indicates putting letters inside.
'number one' becomes 'wee' (both can informally mean urinating).
'essentially' says to take the centre.
The middle letter of 'brasserie' is 's'.
'wee'+'s'='wees'
'dines' inserted into 'wees' is 'WEEDINESS'.

'showing' acts as a link.

Can you help me to learn more?