Inactivity? A pop star will have change of heart (8)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

A , then BEY [o] NCE (pop star Beyoncé), with the middle letter (heart) changed from O to A . I prefer it when the setter specifies what the replacement letter should be, but it’s easy enough to work out in this case. In abeyance = temporarily suspended or no longer used = inactive.