Irish following Troubles, initially laconic (5)
I believe the answer is:
terse
'laconic' is the definition.
('terse' can be a synonym of 'laconic')
'irish following troubles initially' is the wordplay.
'irish' becomes 'erse' (I've seen this before).
'following' means one lot of letters go next to another.
'initially' says to take the initial letters.
The initial letter of 'troubles' is 't'.
'erse' after 't' is 'TERSE'.
(Other definitions for terse that I've seen before include "Abrupt, concise" , "Concise about trees" , "Curt, concise" , "Sententious" , "Short, abrupt" .)