Tofu head smoked, lacking energy (4,4)
I believe the answer is:
bean curd
'tofu' is the definition.
(synonyms)
'head smoked lacking energy' is the wordplay.
'head' becomes 'bean' (bean is a kind of head).
'smoked' becomes 'cured' (I've seen this before).
'lacking' suggests deleting specific letters.
'energy' becomes 'e' (physics symbol as in E=mce).
'cured' with 'e' taken away is 'curd'.
'bean'+'curd'='BEAN CURD'
(Other definitions for bean curd that I've seen before include "food suitable for vegetarian" , "Tofu" .)