Howled at tree, even seed (5)
I believe the answer is:
bayed
'howled' is the definition.
(I've seen this before)
'at tree even seed' is the wordplay.
'at' says to put letters next to each other.
'tree' becomes 'bay' (bay is a kind of tree).
'even' indicates alternate letters (even-numbered letters are used).
The alternate letters of 'seed' are 'ed'.
'bay' put next to 'ed' is 'BAYED'.
(Other definitions for bayed that I've seen before include "Made a lot of noise" , "Made sound like hunting hounds" , "Gave deep cry of a large hunting dog" , "(Of a dog) howled loudly" , "yielded bark" .)