Reveal second question (4)
I believe the answer is:
show
'reveal' is the definition.
('show' can be a synonym of 'reveal')
'second question' is the wordplay.
'second' becomes 's' (common abbreviation**).
'question' becomes 'how' (I've seen this in other clues).
's'+'how'='SHOW'
(Other definitions for show that I've seen before include "Prove; exhibit" , "plausible?" , "Exhibit - present" , "Demonstrate or reveal" , "Musical featuring 'Old Man River'" .)