A lie's found out on the way to the altar (5)
I believe the answer is:
aisle
'way to the altar' is the definition.
(I've seen this in another clue)
'a lie's found out on' is the wordplay.
'found out' is an anagram indicator (discovered out of the normal letter order).
'on' is a charade indicator (letters next to each other).
'lies' anagrammed gives 'isle'.
'a'+'isle'='AISLE'
'the' acts as a link.
(Other definitions for aisle that I've seen before include "'Passage, gangway (5)'" , "Way between seating areas" , "Part of supermarket" , "lateral strip" , "part of theatre?" .)