One's first address -- cheap semi with end collapsing (6,6)
I believe the answer is:
maiden speech
'one's first address' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'cheap semi with end collapsing' is the wordplay.
'with' is a charade indicator (letters next to each other).
'collapsing' is an anagram indicator.
'cheap'+'semi'='cheapsemi'
'cheapsemi' after 'end' is 'endcheapsemi'.
'endcheapsemi' is an anagram of 'MAIDEN SPEECH'.
Can you help me to learn more?
(Other definitions for maiden speech that I've seen before include "original house address" , "Au fait with urban life" , "First words in parliament" , "First ever public address" .)