Like the numerals used in necromancy (5)
I believe the answer is:
roman
'like the numerals' is the definition.
I can't judge whether this defines the answer.
'in necromancy' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ROMAN' is hidden within 'necromancy'.
'used' is the link.
Can you help me to learn more?
(Other definitions for roman that I've seen before include "Norma (anag) -- upright style of print" , "Dominant political power of first centuries AD" , "Sort of face" , "Upright form of type" , "Type of candle, nose etc" .)