Alfred twice given a forage crop (7)
I believe the answer is:
alfalfa
'forage crop' is the definition.
(I've seen this in another clue)
'alfred twice given a' is the wordplay.
'alfred' becomes 'alf' (I can't explain this - if you can you should believe this answer much more).
'twice' shows that letters should be duplicated.
'given' says to put letters next to each other.
'alf' doubled is 'alfalf'.
'alfalf'+'a'='ALFALFA'
Can you help me to learn more?
(Other definitions for alfalfa that I've seen before include "Lucerne, a fodder plant" , "A forage plant" , "odder plant" , "food plant" , "cattle feed" .)