Garden area essential to occupation (5)
I believe the answer is:
patio
'garden area' is the definition.
(part of a garden)
'essential to occupation' is the wordplay.
'essential to' indicates a hidden word (I've seen this in other clues).
'PATIO' can be found hidden inside 'occupation'.
(Other definitions for patio that I've seen before include "Paved area beside house, often in back garden" , "yard" , "Paved outdoor area" , "Spanish court" , "Paved area next to house" .)