Outspoken denial from Berlin cardinal (4)
I believe the answer is:
nine
'cardinal' is the definition.
(a cardinal number)
'outspoken denial from berlin' is the wordplay.
'outspoken' indicates a 'sounds like' (homophone) clue.
'denial from berlin' becomes 'nein' ('no' in German ie in Berlin).
'nein' sounds like 'NINE'.
(Other definitions for nine that I've seen before include "Days Lady Jane 5 ac reigned" , "Number of Muses and days in a Novena" , "A stitch in time saves them" , "Figure" , "Three squared" .)