Number in the crowd to see the composer (5)
I believe the answer is:
holst
'the composer' is the definition.
(Gustav Holst)
'number in the crowd' is the wordplay.
'number' becomes 'l' (L is an example).
'in' indicates putting letters inside.
'the crowd' becomes 'host' (I've seen this before).
'l' placed inside 'host' is 'HOLST'.
'to see' acts as a link.
(Other definitions for holst that I've seen before include "He scored" , "Planets Suite composer" , "Composer of The Planets, d. 1934" , "British composer, 1874-1934" , "Gustav --, English composer" .)