When wild, perhaps, one is singularly seedy! (3)
I believe the answer is:
oat
'when wild' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'one is singularly seedy' is the wordplay.
'one' becomes 'o' (I've seen this in other clues).
'is singularly seedy' becomes 'at' (I am not sure about this - if you are sure you should believe this answer much more).
'o'+'at'='OAT'
'perhaps' acts as a link.
Can you help me to learn more?
(Other definitions for oat that I've seen before include "Food grain" , "Cereal (singular)" , "Basis of porridge" , "Cereal plant" , "Cereal grass" .)