Clue: A last letter has girl and English boy describing love in summerhouse (6)
Answer: GAZEBO
Explanation: Definition: summerhouse
 [A + Z(last letter in the English alphabet) ] **contained in**(has … describing) G,E,B(abbrevs., respectively, for "girl" ***plus***(**and**) "English boy") + O(letter representing 0/love in tennis scores).
I take "G" and "B" as abbreviations in texting (unless a 1st letter indicator is missing?).