Initially serves, and launches volley on volley (5)
I believe the answer is:
salvo
'volley' is the definition.
(synonyms)
'initially serves and launches volley on' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'serves and launches volley on' is 'SALVO'.
(Other definitions for salvo that I've seen before include "Outburst, as of applause" , "Discharge of weapons in unison" , "Ovals (anag)" , "Aussie evangelist" , "concentrated fire" .)