Nerdy expert element of Aztec hierarchy (6)
I believe the answer is:
techie
'nerdy expert' is the definition.
(technology expert)
'element of aztec hierarchy' is the wordplay.
'element of' indicates the answer is hidden within the clue (I've seen this in other clues).
'TECHIE' can be found hidden inside 'aztec hierarchy'.
(Other definitions for techie that I've seen before include "computer expert" , "PC expert" , "Expert in some practical science" , "IT whizz" .)