Bit of Greek text about a number of Brazilians (7)
I believe the answer is:
lambada
'number of brazilians' is the definition.
(Brazilian dance number)
'bit of greek text about a' is the wordplay.
'bit of greek text' becomes 'lambda' (letter of the Greek alphabet).
'about' is an insertion indicator.
'lambda' going around 'a' is 'LAMBADA'.
(Other definitions for lambada that I've seen before include "number of Brazilian revellers" , "Erotic Brazilian dance" , "dance in South America" , "Latin-American dance" , "rhythmic Latin American dance" .)