Clue: Hour of anticipation: Glaswegian singer to turn up and screech (7)
Answer: ULULATE
Explanation: Definition: screech
A reversal ('to turn up' in a down light) of ETA (Estimated Time of Arrival, 'hour of anticipation') plus LULU (Marie McDonald McLaughlin Lawrie, professional name Lulu, grew up in Glasgow, 'Glaswegian singer').