Some needlework, having got pain after marathon (7,6)
I believe the answer is:
running stitch
'some needlework' is the definition.
(running stitch is a kind of needlework)
'pain after marathon' is the wordplay.
'pain' becomes 'stitch' (pain in the body).
'after' means one lot of letters go next to another.
'marathon' becomes 'running' (I can't explain this - if you can you should give a lot more credence to this answer).
'stitch' put after 'running' is 'RUNNING STITCH'.
'having got' acts as a link.
Can you help me to learn more?
(Other definitions for running stitch that I've seen before include "Joiner" , "continuous pain in side" , "Basic needlework style" .)