Ignore ads: terribly pompous (9)
I believe the answer is:
grandiose
'pompous' is the definition.
(I've seen this before)
'ignore ads terribly' is the wordplay.
'terribly' indicates an anagram.
'ignore'+'ads'='ignoreads'
'ignoreads' anagrammed gives 'GRANDIOSE'.
(Other definitions for grandiose that I've seen before include "Pretentiously magnificent" , "Pretentiously imposing -- organised (anag)" , "Ambitious" , "I grade son as affectedly splendid" , "Imposing and pompous, dressed in organdies" .)