That fun-loving fellow Winslow? (7)
I believe the answer is:
playboy
'fellow winslow?' is the definition.
I can't judge whether this defines the answer.
'that fun-loving' is the wordplay.
'that fun' becomes 'play' (synonyms).
'loving' becomes 'boy' (I am not sure about this - if you are sure you should believe this answer much more).
'play'+'boy'='PLAYBOY'
Can you help me to learn more?
(Other definitions for playboy that I've seen before include "American men's lifestyle and entertainment magazine" , "Rich debauchee" , "Rich woman-chaser" , "Casanova" , "Wealthy pleasure-seeker" .)