Break part of arm, did you say? (6)
I believe the answer is:
breach
'break' is the definition.
(I know that break can be written as breach)
'part of arm did you say?' is the wordplay.
I cannot really see how this works, but
'part' could be 'reach' (reach is a kind of part) and 'reach' is present in the answer.
A single letter 'b' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for breach that I've seen before include "Opening - quarrel" , "Gap made in a fortification" , "Rupture, rift" , "Violation of a promise" , "Opening -- infraction" .)