Pretentious boy on Cretan mountain (2-2-2)
I believe the answer is:
la-di-da
'pretentious' is the definition.
(I've seen this before)
'boy on cretan mountain' is the wordplay.
'boy' becomes 'lad' (informal term for boy).
'on' is a charade indicator (letters next to each other).
'cretan mountain' becomes 'Ida' (Mount Ida in Crete).
'lad'+'ida'='LA-DI-DA'
(Other definitions for la-di-da that I've seen before include "Informally, having affected manner of pronunciation" , "Hoity-toity" , "Affectedly genteel" , "Pretentious, snobbish" , "Stuck-up" .)