Discovery holiday by river, falling in however (12)
I believe the answer is:
breakthrough
'discovery' is the definition.
(I've seen this before)
'holiday by river falling in however' is the wordplay.
'holiday' becomes 'break' (I've seen this before).
'by river' becomes 'r' (I am not sure about the 'by' bit.**).
'falling in' is an insertion indicator.
'however' becomes 'though' ('though' can be a synonym of 'however').
'r' going inside 'though' is 'through'.
'break'+'through'='BREAKTHROUGH'
Can you help me to learn more?
(Other definitions for breakthrough that I've seen before include "Important development (eg in research)" , "Sudden significant development" , "Important discovery" , "Significant advance" , "Find" .)