Flipping idiot trapped in a lease dispute (8)
I believe the answer is:
argument
'dispute' is the definition.
(I've seen this before)
'flipping idiot trapped in a lease' is the wordplay.
'flipping' shows that the letters should be reversed in order.
'idiot' becomes 'mug' (I've seen this before**).
'trapped in' is an insertion indicator.
'lease' becomes 'rent' ('rent' can be a synonym of 'lease').
'mug' written backwards gives 'gum'.
'a'+'rent'='arent'
'gum' put within 'arent' is 'ARGUMENT'.
(Other definitions for argument that I've seen before include "Barney" , "Altercation" , "'Debate, row (8)'" , "Debate or dispute" , "Line of reasoning" .)