Beat time having raised orchestral baton, first of all (5)
I believe the answer is:
throb
'beat' is the definition.
(I've seen this before)
'time having raised orchestral baton first of all' is the wordplay.
'time' becomes 't'.
'first of all' indicates taking the first letters.
The initial letters of 'having raised orchestral baton' is 'hrob'.
't'+'hrob'='THROB'
(Other definitions for throb that I've seen before include "Vibrate with rhythm like heart" , "One's heart may do it" , "Pulse" , "Pulsate strongly" , "Strong rhythmic beat" .)