Direct concert with Preludio Tragico to begin with (6)
I believe the answer is:
prompt
'direct' is the definition.
(prompt can mean direct or immediate)
'concert with preludio tragico to begin with' is the wordplay.
'concert' becomes 'prom' (abbreviation for promenade concert).
'with' says to put letters next to each other.
'to begin with' suggests taking the first letters.
The first letters of 'preludio tragico' is 'pt'.
'prom'+'pt'='PROMPT'
(Other definitions for prompt that I've seen before include "Ready" , "Urge - done without delay" , "effective in expedition" , "Speedy - help for forgetful actor" , "Spurs do this" .)