Shoot mouth off in second-class research establishment (4)
I believe the answer is:
blab
'shoot mouth off' is the definition.
I can't tell whether this defines the answer.
'second-class research establishment' is the wordplay.
'second-class' becomes 'b' ().
'research establishment' becomes 'lab' (laboratory).
'b'+'lab'='BLAB'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for blab that I've seen before include "Tell tales" , "Tells tales" , "Reveal secrets by indiscreet talk (colloq.)" , "Spill the beans" , "Give away secrets" .)