Ilippu
7a has no definition. Wordplay is an abbreviation for one particular day, followed by a word for difficult minus its first and last letters.
13a - defn is last two words, word play is anagram ("outrageously") of 2nd and 3rd words
12a
Defn 1st word (an abbreviation of its more common version). Word play - consider what is implied by the spelling of the name, think of an unflattering word for that and take off the last letter.
You presumably have the title implied in the clue. Google that and you will find that there are two participant teams (I did not know any of this - left the UK 30 years ago). One of the teams relates to 7a and 20a, the other to 7d and 20d, which are the four clues without definitions.