Ancient President continues to mock, interrupted by a couple of fellows (9)
I believe the answer is:
jefferson
'ancient president' is the definition.
The definition suggests a singular noun which matches the answer.
'continues to mock interrupted by a couple of fellows' is the wordplay.
I cannot quite see how this works, but
'couple' could be 'eff' (effing is a kind of coupling) and 'eff' is present in the answer.
'of' could be 'o' and 'o' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for jefferson that I've seen is " Thomas -, third US president".)