The doctor joins me in a drink (5)
I believe the answer is:
medoc
'a drink' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'the doctor joins me' is the wordplay.
'the doctor' becomes 'doc' ('doc' can be a synonym of 'doctor').
'joins' means one lot of letters go next to another.
'doc' put after 'me' is 'MEDOC'.
'in' is the link.
Can you help me to learn more?
(Other definitions for medoc that I've seen before include "Wine-growing area" , "region of France" , "Type of wine" , "French intoxicant" , "that's regularly drunk?" .)