Wipe out a boy's name for Ilium (7)
I believe the answer is:
destroy
'wipe out' is the definition.
(I've seen this in another clue)
'a boy's name for ilium' is the wordplay.
'a boy's name' becomes 'des' ().
'for' says to put letters next to each other.
'ilium' becomes 'troy' (synonyms).
'des'+'troy'='DESTROY'
(Other definitions for destroy that I've seen before include "Ruin, put an end to" , "Ruin; pull down" , "Wreck" , "put to death" , "Demolish; pull down" .)