Member of old empire is an upright type (5)
I believe the answer is:
roman
'upright type' is the definition.
(term for upright type as opposed to italic)
'member of old empire is an' is the wordplay.
'member of old empire' becomes 'rom' (I am not sure about this - if you are sure you should believe this answer much more).
'rom'+'an'='ROMAN'
Can you help me to learn more?
(Other definitions for roman that I've seen before include "ancient empire" , "See 19" , "Of an Italian city" , "Latin" , "Dominant political power of first centuries AD" .)