Solve first of conundrums humorist raised (5,2)
I believe the answer is:
clear up
'solve' is the definition.
(I've seen this before)
'first of conundrums humorist raised' is the wordplay.
'first of' says to take the initial letters.
'humorist' becomes 'lear' (Edward Lear).
'raised' becomes 'up' ('up' can be similar in meaning to 'raised').
The initial letter of 'conundrums' is 'c'.
'c'+'lear'+'up'='CLEAR-UP'
(Other definitions for clear up that I've seen before include "Sort out" , "put things in order" , "Tidy; explain; cure" , "Solve a mystery - become brighter" , "iron out" .)