Choose cereal food lacking energy for stirring (8)
I believe the answer is:
electric
'stirring' is the definition.
(I've seen this before)
'choose cereal food lacking energy' is the wordplay.
'choose' becomes 'elect' (electing is a kind of choosing**).
'cereal food' becomes 'rice' (I've seen this before).
'lacking' suggests deleting specific letters.
'energy' becomes 'e' (physics symbol as in E=mcl).
'rice' with 'e' removed is 'ric'.
'elect'+'ric'='ELECTRIC'
'for' is the link.
(Other definitions for electric that I've seen before include "Type of light, fire, shock, etc" , "Emotionally charged" , "This storm has lots of thunder and lightning" , "describing power supplies?" , "Relic etc charged with current" .)