Large bird obtainable from the grocer (3)
I believe the answer is:
roc
'large bird' is the definition.
(mythical giant bird)
'obtainable from the grocer' is the wordplay.
'ROC' is hidden in amongst the letters.
But, I am not sure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for roc that I've seen before include "Arabian Nights bird" , "fabulous bird is seen" , "Gigantic bird of eastern legend - cor!" , "Huge mythical bird of prey" , "Big bird" .)