Communicate one man’s role (6)
I believe the answer is:
impart
'communicate' is the definition.
(imparting is a kind of communicating)
'one man's role' is the wordplay.
'one' becomes 'i' (Roman numeral).
'man' becomes 'm' ().
'role' becomes 'part' (synonyms).
'i'+'m'+'part'='IMPART'
(Other definitions for impart that I've seen before include "Pass on information" , "Hand on" , "Transmit" , "Pass on (knowledge, info)" , "Give - tell" .)