Odd drop of brandy before a dance (5)
I believe the answer is:
rumba
'dance' is the definition.
(rumba is a kind of dance)
'odd drop of brandy before a' is the wordplay.
'odd' becomes 'rum' (I've seen this before).
'drop of' suggests taking the first letters.
'before' means one lot of letters go next to another.
The first letter of 'brandy' is 'b'.
'rum'+'b'+'a'='RUMBA'
(Other definitions for rumba that I've seen before include "Style of dance" , "music one can dance to" , "Strictly round" , "number of steps" , "South American dance" .)