They're not easily broken (6)
I believe the answer is:
habits
'they're not easily broken' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for habits that I've seen before include "Customs or monk's gowns" , "Normal practices in nuns' clothing?" , "Nuns or monks uniforms" , "Established customs" , "Monks' and nuns' clothing" .)