Drunk reluctant to buy round (5)
I believe the answer is:
tight
'drunk' is the definition.
(slang term)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for tight that I've seen before include "Drunk - under control" , "Steaming" , "Inebriated" , "Miserly or blotto" , "Drunk; giving little room" .)