Oddly, speedy anthem's dull (6)
I believe the answer is:
sedate
'dull' is the definition.
(I've seen this before)
'oddly speedy anthem's' is the wordplay.
'oddly' indicates alternate letters (letters in the odd-numbered positions are used).
'speedy'+'anthem'='speedyanthem'
The alternate letters of 'speedyanthem' are 'SEDATE'.
(Other definitions for sedate that I've seen before include "Leisurely" , "boring" , "Decorous" , "Staid and sober" , "Staid - tranquillise" .)