A song receiving review in cheerful readiness (8)
I believe the answer is:
alacrity
'cheerful readiness' is the definition.
'a song receiving review' is the wordplay.
'song' becomes 'lay' (lay is a kind of song**).
'receiving' is an insertion indicator.
'review' becomes 'crit' (I've seen this before).
'lay' going around 'crit' is 'lacrity'.
'a'+'lacrity'='ALACRITY'
'in' is the link.
(Other definitions for alacrity that I've seen before include "Expedition" , "Eagerness, enthusiasm" , "Lively enthusiasm" , "Eager haste" , "Brisk and cheerful readiness" .)