Backing provided by idiot, one with attitude (10)
I believe the answer is:
assistance
'backing' is the definition.
(thesaurus)
'idiot one with attitude' is the wordplay.
'idiot' becomes 'ass' (I've seen this before).
'one with' becomes 'i' (I've seen this in other clues).
'attitude' becomes 'stance' (stance is a kind of attitude**).
'ass'+'i'+'stance'='ASSISTANCE'
'provided by' is the link.
(Other definitions for assistance that I've seen before include "Support" , "Help" , "Aid" .)