Naughty, like a nun who's been expelled? (3,2,5)
I believe the answer is:
out of order
'naughty' is the definition.
(thesaurus)
'nun who's been expelled?' is the wordplay.
I cannot quite understand how this works, but
'expelled?' could be 'out' (I've seen this in another clue) and 'out' is found within the answer.
This explanation may well be incorrect...
'like a' acts as a link.
Can you help me to learn more?
(Other definitions for out of order that I've seen before include "excommunicated?" , "Bust - behaving badly" , "Not going" , "having left monastery?" , "(Mechanism) broken" .)