Physical education instead of food (4)
I believe the answer is:
peas
'food' is the definition.
(I've seen this in another clue)
'physical education instead' is the wordplay.
'physical education' becomes 'pe'.
'instead' becomes 'as' (I am not sure about this - if you are sure you should believe this answer much more).
'pe'+'as'='PEAS'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for peas that I've seen before include "Leguminous plants" , "Seeds in a pod" , "Edible seeds" , "Leguminous seeds" , "Seeded vegetables" .)