The head of this old English newspaper is a slimeball (6)
I believe the answer is:
toerag
'a slimeball' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'the head of this old english newspaper' is the wordplay.
'head of' says to take the initial letters.
'this old english' becomes 'oe'.
'newspaper' becomes 'rag' (informal term for a newspaper).
The initial letter of 'the' is 't'.
't'+'oe'+'rag'='TOERAG'
'is' is the link.
Can you help me to learn more?
(Other definitions for toerag that I've seen before include "Despicable chap" , "despicable sort" , "Despicable person (slang)" , "Scamp" , "contemptible sort" .)