Great and good tucked into alcoholic beverage found in grass (9)
I believe the answer is:
swingeing
'great' is the definition.
(word meaning substantial or severe)
'good tucked into alcoholic beverage found in grass' is the wordplay.
'good' becomes 'g' (abbreviation).
'tucked into' means one lot of letters goes inside another.
'alcoholic beverage' becomes 'wine' (wine is a kind of alcoholic beverage).
'found in' indicates putting letters inside.
'grass' becomes 'sing' (I've seen this in other clues**).
'g' inserted inside 'wine' is 'winge'.
'winge' going inside 'sing' is 'SWINGEING'.
'and' acts as a link.
(Other definitions for swingeing that I've seen before include "Thumping" , "Extreme" , "Painfully severe (cuts, fine)" , "Huge" .)