Funny cartoon includes soldier with singing voice (9)
I believe the answer is:
contralto
'singing voice' is the definition.
(contralto is a kind of singing voice)
'funny cartoon includes soldier' is the wordplay.
'funny' indicates anagramming the letters.
'includes' is an insertion indicator.
'soldier' becomes 'lt'.
'cartoon' is an anagram of 'contrao'.
'contrao' going around 'lt' is 'CONTRALTO'.
'with' is the link.
(Other definitions for contralto that I've seen before include "Lowest female singing voice" , "Lowest range for a woman singer" , "Female voice of the lower register." , "Total corn! (anag)" , "Low female voice" .)