Old person regularly sampling jazz at beach (5)
I believe the answer is:
aztec
'old person' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for aztec that I've seen before include "Early Mexican civilisation" , "Irish lower house" , "Old Mexican Indian" , "Native of old Mexico" , "Conquered Mexican" .)