"PROHIBITIONIST CHAP WITH COMMERCIAL POLICY”? (6,8)

I believe the answer is:

banner headline

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'prohibitionist chap with commercial policy?' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'prohibitionist chap with commercial policy?' is the wordplay.
'prohibitionist' becomes 'banner' (I can't justify this - if you can you should believe this answer much more).
'chap' becomes 'he'.
'with' means one lot of letters go next to another.
'commercial' becomes 'ad' (abbreviation for advertisement).
'policy?' becomes 'line' (as in the party line).
'banner'+'he'+'ad'+'line'='BANNER HEADLINE'

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(Other definitions for banner headline that I've seen before include "Newspaper front page item" , "Streamer" .)

I've seen this clue in The Times.

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