Adult ordered a claret according to individually priced menu (1,2,5)
I believe the answer is:
a la carte
'according to individually priced menu' is the definition.
(a la carte means from a set menu)
'adult ordered a claret' is the wordplay.
'adult' becomes 'a' (abbreviation).
'ordered' is an anagram indicator.
'a'+'claret'='aclaret'
'aclaret' anagrammed gives 'lacarte'.
'a'+'lacarte'='A LA CARTE'
(Other definitions for a la carte that I've seen before include "With each dish chosen separately" , "Menu with dishes listed and priced separately" , "Chosen from full menu" , "Menu with differently priced choices" , "not fixed at table" .)