Problem generated by Iago’s opening lines (3)
I believe the answer is:
ill
'problem' is the definition.
(as in the ills of society)
'iago's opening lines' is the wordplay.
'opening' says to take the initial letters.
'lines' becomes 'll' (an abbreviation for line written twice).
The first letter of 'iago' is 'i'.
'i'+'ll'='ILL'
'generated by' acts as a link.
(Other definitions for ill that I've seen before include "I will (abbrev.) (1'2)" , "Sickly" , "Hardly - sick" , "In bad health" , "Infirm" .)