Crossword Genius

Working Greek hopes staff refrain from using drugs? (4,3,3,5)

Ross

I believe the answer is:

keep off the grass

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'refrain from using drugs?' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'working greek hopes staff' is the wordplay.
'working' is an anagram indicator.
'greek'+'hopes'+'staff'='greekhopesstaff'
'greekhopesstaff' with letters rearranged gives 'KEEP OFF THE GRASS'.

Can you help me to learn more?

(Other definitions for keep off the grass that I've seen before include "Don't reach the green" , "Warning by turf" , "sign - one seen in park?" , "Sign on lawn" , "avoid drug usage!" .)

I've seen this clue in The Guardian.
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