Sportsman who has a fling (7)
I believe the answer is:
pitcher
'sportsman who has a fling' is the definition.
'pitcher' can be an answer for 'sportsman' (I have seen 'American sportsman' mean 'pitcher' so perhaps 'sportsman' could also mean 'pitcher'). I am not certain of the rest of the definition.
'sportsman who has a fling' is the wordplay.
'sportsman who' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'has' means one lot of letters go next to another.
'a fling' becomes 'pitch' (I've seen this before).
'er' after 'pitch' is 'PITCHER'.
Can you help me to learn more?
(Other definitions for pitcher that I've seen before include "One throwing" , "able to hold a lot of beer" , "Earthenware vessel" , "one getting walked all over?" , "Baseball player - bowl" .)