Traditionalists hold out with loco beliefs in the end (3,6)
I believe the answer is:
old school
'traditionalists' is the definition.
(I've seen this in another clue)
'hold out with loco beliefs in the end' is the wordplay.
'out with' indicates anagramming the letters (out can mean wrong or inaccurate).
'in the end' says to take the final letters.
The final letter of 'beliefs' is 's'.
'loco'+'s'='locos'
'hold' anagrammed with 'locos' gives 'OLD-SCHOOL'.
(Other definitions for old school that I've seen before include "Group favouring conservative practices" , "Doing things the same way as before" , "Where one was educated (with a tie?)" , "sort of tie?" , "a bunch of conservative types" .)