Partner said why date's going wrong, initially (6)
I believe the answer is:
steady
'partner' is the definition.
(I've seen this before)
'said why date's going wrong initially' is the wordplay.
'said' shows a homophone (sound like).
'going wrong' indicates an anagram.
'initially' says to put letters next to each other (some letters go before others).
'why' is a homophone of 'y'.
'dates' anagrammed gives 'stead'.
'y' after 'stead' is 'STEADY'.
(Other definitions for steady that I've seen before include "Holds course - ...... as she goes" , "Well-balanced" , "Pull yourself together" , "Balanced, not shaky" , "One's regular partner" .)