Mock, eating one's hot and cold food
I believe the answer is:
fish cake
'food' is the definition.
(fish cake is a kind of food)
'mock eating one's hot and cold' is the wordplay.
'mock' becomes 'fake'.
'eating' is an insertion indicator.
'one's hot' becomes 'ish' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' means one lot of letters go next to another.
'cold' becomes 'c' (eg on taps).
'ish'+'c'='ishc'
'fake' placed around 'ishc' is 'FISH CAKE'.
Can you help me to learn more?
(Other definitions for fish cake that I've seen before include "Ask chief (anag.)" , "Fried seafood patty" , "Fried seafood dish" , "Fried ball of potato and cod, say" , "Food item" .)