For one famous DJ retirement's beginning in Spain – goodbye Jack (5,4)
I believe the answer is:
radio star
'for one famous dj' is the definition.
I can't tell whether this definition defines the answer.
'retirement's beginning in spain goodbye jack' is the wordplay.
'beginning' suggests taking the first letters.
'in spain goodbye' becomes 'adios' (I am not sure about this - if you are sure you should believe this answer much more).
'jack' becomes 'tar' (both are informal terms for sailor).
The initial letter of 'retirements' is 'r'.
'r'+'adios'+'tar'='RADIO STAR'
Can you help me to learn more?
(Other definitions for radio star that I've seen before include "Sky feature" , "Important broadcaster" .)