Joins without fifty twists (5)
I believe the answer is:
slews
'twists' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
'joins without fifty' is the wordplay.
'joins' becomes 'sews' (I can't justify this - if you can you should give a lot more credence to this answer).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'fifty' becomes 'l' (Roman numeral).
'sews' going around 'l' is 'SLEWS'.
Can you help me to learn more?
(Other definitions for slews that I've seen before include "Skids, bringing a vehicle's back-end around" , "lurches violently" .)