Material used by a fathead and a hothead (5)
I believe the answer is:
cloth
'material' is the definition.
(I know that material can be written as cloth)
'a fathead and a hothead' is the wordplay.
'a fathead' becomes 'clot' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' is a charade indicator (letters next to each other).
'a hothead' becomes 'h' (head letter of 'hot').
'clot'+'h'='CLOTH'
'used by' is the link.
Can you help me to learn more?
(Other definitions for cloth that I've seen before include "Gingham, say" , "ministers" , "Woven material" , "Sails" , "The clergy" .)