Bad mark for a boy who gets out of line (5)
I believe the answer is:
stain
This could be a double definition.
'bad mark for a boy who gets' is the first definition.
'stain' can be an answer for 'bad mark' (I've seen this in another clue). I am not certain of the rest of the definition.
'line' is the second definition.
(thesaurus)
'out of' acts as a link.
Can you help me to learn more?
(Other definitions for stain that I've seen before include "Tarnish" , "Discolouration" , "Unsightly mark" , "Smear" , "Mark with colour, dirt" .)