Sentimental cast sing a lot, crying initially (9)
I believe the answer is:
nostalgic
'sentimental' is the definition.
(I've seen this before)
'cast sing a lot crying initially' is the wordplay.
'cast' is an anagram indicator (letters are dispersed or cast around).
'initially' suggests taking the first letters.
The first letter of 'crying' is 'c'.
'sing'+'a'+'lot'='singalot'
'singalot' anagrammed gives 'nostalgi'.
'nostalgi'+'c'='NOSTALGIC'
(Other definitions for nostalgic that I've seen before include "Looking backwards" , "Sentimental about the past" , "down Memory Lane" , "longing for home" , "Fondly remembering the past" .)