Old poet, French one, hit in baseball stadium (4,3)
I believe the answer is:
home run
'hit in baseball stadium' is the definition.
'home run' can be an answer for 'hit' (home run is a kind of hit). I'm unsure of the 'in baseball stadium' bit.
'old poet french one' is the wordplay.
'old poet' becomes 'homer' (ancient poet).
'french one' becomes 'un' ('one' in French).
'homer'+'un'='HOME RUN'
Can you help me to learn more?
(Other definitions for home run that I've seen before include "complete tour of bases" , "Baseball achievement" , "Good baseball hit" , "Baseball score" , "result of big hit in US" .)