River in south drained in the year, before November (7)
I believe the answer is:
shannon
'river' is the definition.
(I've seen this before)
'south drained in the year before november' is the wordplay.
'drained' means to remove the middle letters.
'in the year' becomes 'anno' (I've seen this before).
'before' is a charade indicator (letters next to each other).
'november' becomes 'N' (phonetic alphabet: alpha, bravo, charlie etc.).
'south' with its middle taken out is 'sh'.
'sh'+'anno'+'n'='SHANNON'
'in' is the link.
(Other definitions for shannon that I've seen before include "Irish 10" , "Ireland's longest river" , "Major Irish river" , "River in Irish Republic" , "current in Ireland" .)