Essential

19 clues
Key
Basic
Vital
Needed
Required
Intrinsic
Must-have
Necessary
Chief point
Not optional
Indispensable
Indispensible
Most important
___ sine qua non
Hardly necessary
Hardly extraneous
Vitally important
Like many nutrients
Absolutely necessary
Similar answers:
Abbesses
Abscesses
Accessed
Accessedfed
Accesses
Actresses
Actressesbrittandwhitty
Addressed
Addressedtokill
Addressee
Addressees
Addresser
Addressers
Addresses
Adesse
Adjustdesserts
Adresse
Aggresses
Agnesseve
Airvessel