Musician's skill in this grade sadly lacking, ultimately (5-7)

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

IN THIS GRADE* lackin G; in my dotage, I am fortunate enough to sing in a semi-professional choir with many excellent singers. While my sight-reading is poor, I have been praised by our chorusmaster for my listening. When I told my wife this, she roared with laughter.