He doesn't tell terrible lies (6)
I believe the answer is:
fibber
'he doesn't tell terrible lies' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he' is the wordplay.
I cannot really understand how this works, but
'he' could be 'ber' and 'ber' is found within the answer.
The remaining letters 'fib' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for fibber that I've seen before include "Liar" , "Teller of little lies" , "Storyteller" , "One who tells porkies" , "Teller of white lies" .)