Denies one is missing essentials (5)
I believe the answer is:
needs
'denies one is missing essentials' is the definition.
I can't tell whether this definition defines the answer.
'denies one is missing essentials' is the wordplay.
'one' becomes 'i' (Roman numeral).
'is missing' suggests deleting specific letters.
'essentials' indicates an anagram.
'denies' with 'i' removed is 'denes'.
'denes' with letters rearranged gives 'NEEDS'.
Can you help me to learn more?
(Other definitions for needs that I've seen before include "Things that are wanted" , "Requires or lacks" , "Requirements" , "shopping-list, say" , "Wants, requires" .)