Musical piece, likewise with a beat, coming up (6)
I believe the answer is:
sonata
'musical piece' is the definition.
(I've seen this before)
'likewise with a beat coming up' is the wordplay.
'likewise' becomes 'so' (synonyms).
'with' means one lot of letters go next to another.
'beat' becomes 'tan' (I've seen this before).
'coming up' is a reversal indicator.
'a'+'tan'='atan'
'atan' written backwards gives 'nata'.
'so'+'nata'='SONATA'
(Other definitions for sonata that I've seen before include "Solo piano composition" , "Composition for 1 or 2 instruments, with 3 or 4 movements" , "Instrumental composition for soloist" , "Musical composition for a solo instrument" , "just for one or two players?" .)