Pressure on what could be the atom (8)
I believe the answer is:
particle
'the atom' is the definition.
(synonyms)
'pressure on' is the wordplay.
I cannot quite see how this works, but
'pressure' could be 'p' (abbreviation) and 'p' is found within the answer.
The remaining letters 'article' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'what could be' acts as a link.
Can you help me to learn more?
(Other definitions for particle that I've seen before include "Small amount" , "One word" , "Grain, tiny piece" , "Minute piece of matter" , "Minute portion" .)