Furore when a drunken sot joins the marines (5)
I believe the answer is:
storm
'furore' is the definition.
(I've seen this before)
'a drunken sot joins the marines' is the wordplay.
'a drunken' is an anagram indicator.
'joins' is a charade indicator (letters next to each other).
'the marines' becomes 'RM' (abbreviation for 'Royal Marines').
'sot' is an anagram of 'sto'.
'sto'+'rm'='STORM'
'when' is the link.
(Other definitions for storm that I've seen before include "violent assault" , "Very unfavourable climate" , "Feature of weather" , "Charge" , "Squall" .)