He composed letter after a bit of work (4)

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

Alban, composer of (mostly) 12-tone music, more Radio 3 than Classic FM. Nice touch here: the letter after A is B, followed by ERG, “The CGS unit of work, equal to 10 −7 joules”, which doesn’t sound like much.