Material depicting essential clue linked to third puzzle (6)
I believe the answer is:
chintz
'material' is the definition.
(I know that chintz is a type of material)
'essential clue linked to third puzzle' is the wordplay.
'essential' becomes 'c' (I can't justify this - if you can you should give a lot more credence to this answer).
'clue' becomes 'hint' (synonyms).
'linked to' is a charade indicator (letters next to each other).
'third puzzle' becomes 'z' (3rd letter of 'puzzle').
'c'+'hint'+'z'='CHINTZ'
'depicting' is the link.
Can you help me to learn more?
(Other definitions for chintz that I've seen before include "Brightly printed cotton fabric" , "Floral cotton cloth" , "Patterned fabric for soft furnishings" , "Glazed cotton print" , "Heinrich --, 16th-century German composer" .)