Players love runs by Gunners around box (9)
I believe the answer is:
orchestra
'players' is the definition.
(group playing music)
'love runs by gunners around box' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'runs by' becomes 'r' (cricket abbreviation. I am not sure about the 'by' bit.).
'gunners' becomes 'RA' (Royal Artillery).
'around' is an insertion indicator.
'box' becomes 'chest' (chest is a kind of box).
'r'+'ra'='rra'
'rra' placed around 'chest' is 'rchestra'.
'o'+'rchestra'='ORCHESTRA'
Can you help me to learn more?
(Other definitions for orchestra that I've seen before include "Brass, woodwind, strings and percussion" , "kitchen setting?" , "many players" , "Large band playing classical music" , "Large music group" .)