Host of guests writing cool new number one? (9)
I believe the answer is:
innkeeper
'host of guests' is the definition.
'innkeeper' can be an answer for 'host' (synonyms). I'm unsure of the 'of guests' bit.
'cool new number one?' is the wordplay.
'cool' becomes 'in' ('in' can mean fashionable or cool).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'number one?' becomes 'keeper' (football goal keepers normally wear the number i).
'in'+'n'+'keeper'='INNKEEPER'
'writing' is the link.
Can you help me to learn more?
(Other definitions for innkeeper that I've seen before include "Tavern owner" , "Manager who made extra provision for visitors" , "Accommodating type" , "Job" , "Publican" .)