More or less self-possessed presenter needing no introduction (6)
I believe the answer is:
almost
'more or less' is the definition.
(thesaurus)
'self-possessed presenter needing no introduction' is the wordplay.
'self-possessed' becomes 'alm' (I can't explain this - if you can you should give a lot more credence to this answer).
'presenter' becomes 'host' (I've seen this before).
'needing no introduction' means to remove the first letter.
'host' with its first letter taken off is 'ost'.
'alm'+'ost'='ALMOST'
Can you help me to learn more?
(Other definitions for almost that I've seen before include "practically" , "Well-nigh" , "Nearly, not quite" , "Not totally" , "As good as" .)