Leaders in Puerto Rico avoid introduction (7)
I believe the answer is:
prelude
'introduction' is the definition.
(I've seen this in another clue)
'leaders in puerto rico avoid' is the wordplay.
'leaders in' indicates taking the first letters.
'avoid' becomes 'elude' (eluding is a kind of avoiding).
The first letters of 'puerto rico' is 'pr'.
'pr'+'elude'='PRELUDE'
(Other definitions for prelude that I've seen before include "Overture" , "Introductory passage" , "Introductory piece of music" , "Curtain-raiser" , "Introductory part, say of poem" .)