Noel Edmonds finally involved in its March broadcast (9)
I believe the answer is:
christmas
'noel' is the definition.
('Christmas' can be a synonym of 'noel')
'edmonds finally involved in its march broadcast' is the wordplay.
'finally' suggests the final letters.
'involved in' indicates putting letters inside.
'broadcast' indicates anagramming the letters.
The last letter of 'edmonds' is 's'.
'its'+'march'='itsmarch'
'itsmarch' is an anagram of 'chritmas'.
's' placed within 'chritmas' is 'CHRISTMAS'.
(Other definitions for christmas that I've seen before include "Christian festival" , "Winter festival" , "Yuletide" , "Winter feast" , "The festive season harms tics, oddly" .)