Let down daughter and sip a Pinot, drunk (10)
I believe the answer is:
disappoint
'let down' is the definition.
(I know that let down can be written as disappoint)
'daughter and sip a pinot drunk' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'and' means one lot of letters go next to another.
'drunk' indicates anagramming the letters.
'sip'+'a'+'pinot'='sipapinot'
'sipapinot' with letters rearranged gives 'isappoint'.
'd'+'isappoint'='DISAPPOINT'
(Other definitions for disappoint that I've seen before include "Fail to satisfy" , "Let down" .)