Crossword Genius

Beef? Older relative eats duck (5)

Ross

I believe the answer is:

(Other definitions for groan that I've seen before include "Organ (anag) - lament", "Titus -- (Mervyn Peake)", "Express disappointment, pain", "Sound pained; Gormenghast earldom", "Sound of one in pain".)

I've seen this clue in The Independent.