Found in bathroom, has been arranging bash at home (9)
I believe the answer is:
washbasin
'found in bathroom' is the definition.
(I know that washbasin is in bathroom.)
'been arranging bash at home' is the wordplay.
'been' becomes 'was' (being is a kind of being).
'arranging' is an anagram indicator.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'bash' with letters rearranged gives 'hbas'.
'was'+'hbas'+'in'='WASHBASIN'
'has' acts as a link.
(Other definitions for washbasin that I've seen before include "home bathroom fitting?" , "Shallow sink" , "Ablutions bowl" , "Bathroom fixture" .)