Son seen in excited crowd (4)
I believe the answer is:
host
'crowd' is the definition.
(both can mean a large number of people)
'son seen in excited' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'seen in' is an insertion indicator.
'excited' becomes 'hot' (I've seen this in other clues).
's' going inside 'hot' is 'HOST'.
(Other definitions for host that I've seen before include "TV presenter; large number" , "Does he invite a large number?" , "Army; publican" , "Present" , "Party-giver" .)