Pressure on worker to sound exhausted (4)
I believe the answer is:
pant
'to sound exhausted' is the definition.
I can't tell whether this definition defines the answer.
'pressure on worker' is the wordplay.
'pressure' becomes 'p' (scientific abbreviation).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'worker' becomes 'ant' (worker is a type of ant).
'p'+'ant'='PANT'
Can you help me to learn more?
(Other definitions for pant that I've seen before include "Breathe noisily after running" , "Sound out of breath" , "Struggle for breath" , "Long" , "Breathe hard" .)