It's slang for "a thrill"? Precisely! (4)
I believe the answer is:
bang
'precisely' is the definition.
(I've seen this before)
'it's slang for a thrill?' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bang that I've seen before include "Explosive noise" , "A loud report or a collision" , "Completely modern" , "Sudden loud noise like an explosion" , "Strike violently" .)