More revolting, gratuitous, extreme fiction found in Iraqi city, in the past (6)
I believe the answer is:
Here is my best explanation:
'more revolting' is the definition.
(I've seen this before)
'gratuitous extreme fiction found in iraqi city in the past' is the wordplay.
I cannot quite see how this works, but
'fiction' could be 'lie' (I've seen this in other clues) and 'lie' is present in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for uglier that I've seen before include "with worse features", "More unsightly", "More hideous", "More repulsive", "Less pleasing to the sight", "More deficient in beauty", "More unattractive or repellent to the eye", "More displeasing to the senses", "Less pleasing to look at" and "Less appealing".)