Bones of setter so long with painful stress injury (9)
I believe the answer is:
metatarsi
'bones' is the definition.
(I've seen this before)
'setter so long with painful stress injury' is the wordplay.
'setter' becomes 'me' (the setter of the clue).
'so long' becomes 'ta ta' (both are ways of saying goodbye).
'with painful stress injury' becomes 'rsi' (I can't explain this - if you can you should believe this answer much more).
'me'+'tata'+'rsi'='METATARSI'
'of' is the link.
Can you help me to learn more?
(Other definitions for metatarsi that I've seen before include "bones" , "Parts of the feet" .)