Think I've got the theme, the 7 word phrase, and possibly the crossed definitions (are they very central?)
But as for the colour?
The theme implies one colour, which with
1d gives a day you're likely to be dumped
12a gives a playing card
25a gives a rock band
20a implies an associated flower
and gives nothing with the other two interchanged words, as far as I can see
But a similar, deeper colour gives more coherent answers e.g. with
1d Rock song
12a rock band
25a singer
24d a Twitter page
20a a colour