Mae West quip used occasionally when they join (4,2)
I believe the answer is:
meet up
'mae west quip used occasionally when they' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'join' is the wordplay.
I cannot really see how this works, but
'join' could be 'meet' (meeting is a kind of joining) and 'meet' is found within the answer.
The remaining letters 'up' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for meet up that I've seen is " Have a rendezvous".)