Some author describes crowd (5)
I believe the answer is:
horde
'crowd' is the definition.
(I know that horde is a type of crowd)
'some author describes' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'HORDE' can be found hidden inside 'author describes'.
(Other definitions for horde that I've seen before include "Great crowd" , "Many people" , "Nomadic army" , "Vast multitude" , "Migratory tribe; army" .)