Christian starting off with a measure of whisky? (5)
I believe the answer is:
optic
'a measure of whisky?' is the definition.
(an optic is used for measuring out spirits)
'christian starting off' is the wordplay.
'christian' becomes 'Coptic' (as in the Coptic Church).
'starting off' means to remove the first letter (the letter which starts the word is removed).
'coptic' with its initial letter removed is 'OPTIC'.
'with' acts as a link.
(Other definitions for optic that I've seen before include "Device for measuring gin etc" , "Relating to the eyes" , "Ocular" , "Bar measure" , "Alcoholic drink dispenser" .)