Cook made to keep back especially grand rum (8)
I believe the answer is:
demerara
'grand rum' is the definition.
'demerara' can be an answer for 'rum' (demerara is a type of rum). I am not certain of the 'grand' bit.
'cook made to keep back especially' is the wordplay.
'cook' indicates an anagram.
'to keep' means one lot of letters goes inside another.
'back' says the letters should be written backwards.
'especially' becomes 'rare' (I can't justify this - if you can you should give a lot more credence to this answer).
'rare' written backwards gives 'erar'.
'made' anagrammed gives 'dema'.
'dema' enclosing 'erar' is 'DEMERARA'.
Can you help me to learn more?
(Other definitions for demerara that I've seen before include "Type of brown sugar" , "That's sweet!" , "sweetener" , "(Light-brown) sugar" , "Source of sweetness" .)