Cast odd series, The Ashes? (5)
I believe the answer is:
trees
'ashes?' is the definition.
(ash is a kind of tree)
'cast odd series the' is the wordplay.
'cast' is an anagram indicator (letters are dispersed or cast around).
'odd' means one should take alternating letters.
'series'+'the'='seriesthe'
The alternate letters of 'seriesthe' are 'srete'.
'srete' is an anagram of 'TREES'.
(Other definitions for trees that I've seen before include "Tall, perennial, woody plant" , "Steer into the plants" , "Elms, pines etc" , "Woods" , "''I see ... of green / Red roses too'' (What a Wonderful World)" .)