US toilet sat on by dodgy aimer (8)
I believe the answer is:
american
'us' is the definition.
(I've seen this before)
'toilet sat on by dodgy aimer' is the wordplay.
'toilet' becomes 'can' ('can' can be a synonym of 'toilet').
'sat on by' says to put letters next to each other.
'dodgy' indicates an anagram.
'aimer' is an anagram of 'ameri'.
'can' after 'ameri' is 'AMERICAN'.
(Other definitions for american that I've seen before include "The nationality is in camera, oddly" , "Main race (anag.)" , "Native to the USA" , "US citizen in Cinerama (8)" , "Game played on a gridiron" .)