Enduring Eagles remix, shaking head (7)
I believe the answer is:
ageless
'enduring' is the definition.
(I've seen this in another clue)
'eagles remix shaking head' is the wordplay.
'remix' is an anagram indicator (letters mixed up).
'head' suggests taking the first letters.
The first letter of 'shaking' is 's'.
'eagles' anagrammed gives 'ageles'.
'ageles'+'s'='AGELESS'
(Other definitions for ageless that I've seen before include "Always youthful" , "not getting on" , "Perpetually young" , "Sea-legs (anag.)" , "Never appearing to grow old" .)