Thermos designed for some parents (7)
I believe the answer is:
mothers
'some parents' is the definition.
(mother is a kind of parent)
'thermos designed' is the wordplay.
'designed' is an anagram indicator (designed with the letters).
'thermos' anagrammed gives 'MOTHERS'.
'for' acts as a link.
(Other definitions for mothers that I've seen before include "Parents" , "Dams" , "Fusses over" .)