In parliament, stand up to remove one waving a trumpet (8)
I believe the answer is:
daffodil
'one waving a trumpet' is the definition.
(many daffodils have parts known as trumpets)
'in parliament stand up to remove' is the wordplay.
'in' means one lot of letters goes inside another.
'parliament' becomes 'dail' (I've seen this before).
'stand up' shows that the letters should be reversed in order (in a down clue, the word stands upside down).
'to remove' becomes 'doff' (I've seen this before).
'doff' written backwards gives 'ffod'.
'dail' enclosing 'ffod' is 'DAFFODIL'.
(Other definitions for daffodil that I've seen before include "Yellow spring flower beloved of Wordsworth" , "Type of 24 across" , ""Welsh" flower?" , "Plant of the genus Narcissus" , "Lent lily" .)