Not to mention the outlandish bit (3)
I believe the answer is:
and
'not' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'mention the outlandish bit' is the wordplay.
'bit' says the answer is hidden in the clue.
'AND' is hidden in the letters of 'mention outlandish'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for and that I've seen before include "It's used to connect words, clauses or sentences" , "moreover" , "Together with" , "Word to connect" , "Most-used conjunction in English" .)