The drink Jock has with a companion (6)
I believe the answer is:
scotch
'the drink' is the definition.
(Scotch is an example)
'jock has with a companion' is the wordplay.
I cannot quite see how this works, but
'jock' could be 'scot' and 'scot' is found within the answer.
'companion' could be 'ch' (Companion of Honour) and 'ch' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for scotch that I've seen before include "Cut - wedge - whisky" , "Put an end to, say rumour" , "Put paid to - whisky" , "Frustrate; quash" , "Finish off" .)