Nonsense about fifty times three? (6)
I believe the answer is:
triple
'times three?' is the definition.
'triple' can be an answer for 'three?' (thesaurus). I'm not certain of the 'times' bit.
'nonsense about fifty' is the wordplay.
'nonsense' becomes 'tripe' (informal term for nonsense or false information).
'about' means one lot of letters goes inside another.
'fifty' becomes 'l' (Roman numeral).
'tripe' enclosing 'l' is 'TRIPLE'.
Can you help me to learn more?
(Other definitions for triple that I've seen before include "make much longer" , "Threefold, treble" , "Multiply by three" , "Three times" , "Let rip with a threesome" .)