Passage with Auntie Cathy beginning convoluted trip (11)
I believe the answer is:
hallucinate
'trip' is the definition.
(thesaurus)
'passage with auntie cathy beginning convoluted' is the wordplay.
'passage' becomes 'hall' (hall is a kind of passage).
'with' is a charade indicator (letters next to each other).
'beginning' says to take the initial letters.
'convoluted' indicates an anagram.
The initial letter of 'cathy' is 'c'.
'auntie'+'c'='auntiec'
'auntiec' with letters rearranged gives 'ucinate'.
'hall'+'ucinate'='HALLUCINATE'
(Other definitions for hallucinate that I've seen before include "See things that aren't there" , "Experience unreal things" , "Have strange visions" , "See what isn't there" .)