First course was, like, this high! (4)
I believe the answer is:
soup
'first course' is the definition.
(I've seen this before)
'like this high' is the wordplay.
'like this' becomes 'so'.
'high' becomes 'up' (associated in meaning).
'so'+'up'='SOUP'
'was' acts as a link.
(Other definitions for soup that I've seen before include "Liquid - course" , "Eskimo people" , "Mulligatawny or borscht?" , "Stolen plate melted down" , "First course" .)