Man, after one day, displaying specific way of speaking (5)
I believe the answer is:
idiom
'way of speaking' is the definition.
(I've seen this before)
'man after one day' is the wordplay.
'man' becomes 'iom' (abbreviation for Isle of Man).
'after' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'day' becomes 'd' (abbreviation for day).
'i'+'d'='id'
'iom' after 'id' is 'IDIOM'.
'displaying specific' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for idiom that I've seen before include "Style of speaking characteristic of a specific group" , "Language peculiar to a particular group" , "Characteristic language of people or group" , "Use of words" , "'Break a leg' or 'miss the boat'" .)