Plans extremely sexy retro dance with origin in Ilford (7)
I believe the answer is:
syllabi
'plans' is the definition.
(more than one syllabus)
'extremely sexy retro dance with origin in ilford' is the wordplay.
'extremely' suggests removing the centre (only the extremes of the word are used).
'retro' is a reversal indicator (retro is Latin for 'backwards').
'dance' becomes 'ball' (ball is a kind of dance).
'with' is a charade indicator (letters next to each other).
'origin in' indicates taking the first letters.
'sexy' with its centre removed is 'sy'.
The first letter of 'ilford' is 'i'.
'ball' back-to-front is 'llab'.
'sy'+'llab'+'i'='SYLLABI'
(Other definitions for syllabi that I've seen before include "Details of courses" , "course programmes!" , "Subjects for courses" , "exam documentation" , "course details" .)