Volley made by Sarah playing against Oscar (5)
I believe the answer is:
salvo
'volley' is the definition.
(I've seen this before)
'sarah playing against oscar' is the wordplay.
'sarah' becomes 'sal' (Sally is a common pet form of Sarah).
'playing' becomes 'v' ('playing' can mean 'versus' in sports).
'against' means one lot of letters go next to another.
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'sal'+'v'+'o'='SALVO'
'made by' is the link.
(Other definitions for salvo that I've seen before include "Simultaneous discharge of fire" , "Simultaneous artillery fire" , "A number of shots" , "Several rounds" , "Outburst, as of applause" .)