Unusually striking way to avoid a commercial overhead? (10)
I believe the answer is:
skywriting
'commercial overhead?' is the definition.
(advertisement formed by smoke trails in the sky)
'unusually striking way to avoid a' is the wordplay.
'unusually' is an anagram indicator.
'to avoid' is a deletion indicator.
'striking'+'way'='strikingway'
'strikingway' with 'a' taken away is 'strikingwy'.
'strikingwy' anagrammed gives 'SKYWRITING'.
(Other definitions for skywriting that I've seen before include "Smoke trail text" , "Vapour trail messages" , "Messages created by planes" .)