Idle after breaking toes? That's abstruse! (8)
I believe the answer is:
esoteric
'abstruse' is the definition.
(I've seen this in another clue)
'idle after breaking toes?' is the wordplay.
'idle' becomes 'eric' (I've seen this before).
'after' is a charade indicator (letters next to each other).
'breaking' is an anagram indicator.
'toes' with letters rearranged gives 'esot'.
'eric' after 'esot' is 'ESOTERIC'.
'that's' is the link.
(Other definitions for esoteric that I've seen before include "Intended for the few" , "hidden" , "Mysterious to all but a chosen few" , "Mystic" , "Secret; taught to few" .)