Being drunk, note, is a tricky situation (5,4)
I believe the answer is:
tight spot
'tricky situation' is the definition.
'being drunk note' is the wordplay.
'being drunk' becomes 'tight' (slang term).
'note' becomes 'spot' (I am not sure about this - if you are sure you should believe this answer much more).
'tight'+'spot'='TIGHT SPOT'
'is a' is the link.
Can you help me to learn more?
(Other definitions for tight spot that I've seen before include "Fix" , "Difficult situation" , "hole" , "predicament" .)