Perhaps one draws the line at breaking them (5)
I believe the answer is:
rules
'perhaps one draws' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'line at breaking them' is the wordplay.
I cannot quite see how this works, but
'line' could be 'l' (used when specifying particular lines from a poem) and 'l' is found in the answer.
The remaining letters 'rues' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'the' is the link.
Can you help me to learn more?
(Other definitions for rules that I've seen before include "game in Australia" , "following Queensberry?" , "Governs; regulations" , "See 7" , "is supreme, OK?" .)