Confound nightclub with start of manic attack (9)
I believe the answer is:
discomfit
'confound' is the definition.
(thesaurus)
'nightclub with start of manic attack' is the wordplay.
'nightclub' becomes 'disco' (a disco is a club for dancing).
'with' is a charade indicator (letters next to each other).
'start of' suggests taking the first letters.
'attack' becomes 'fit' (fit is a kind of attack).
The first letter of 'manic' is 'm'.
'disco'+'m'+'fit'='DISCOMFIT'
(Other definitions for discomfit that I've seen before include "cause bafflement" , "Embarrass" , "Make uneasy or embarrassed" , "Upset" , "Rattle" .)