To love a girl is quite permissible (4)
I believe the answer is:
okay
'quite permissible' is the definition.
'okay' can be an answer for 'permissible' (thesaurus). I am not sure about the 'quite' bit.
'to love a girl' is the wordplay.
'to love' becomes 'o' (In tennis, 'love' means 'zero').
'a girl' becomes 'kay' ().
'o'+'kay'='OKAY'
'is' is the link.
Can you help me to learn more?
(Other definitions for okay that I've seen before include "Permissible; fairly good" , "Common jargon for yes, all right" , "Not terrific but acceptable" , "Fairly good; approve" , "in order" .)