Pressure on freedom of action is commonplace (9)
I believe the answer is:
platitude
'commonplace' is the definition.
(I know that commonplace can be written as platitude)
'pressure on freedom of action' is the wordplay.
'pressure' becomes 'p' (scientific abbreviation).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'freedom of action' becomes 'latitude' (I've seen this in another clue).
'p'+'latitude'='PLATITUDE'
'is' is the link.
(Other definitions for platitude that I've seen before include "Trite or insincere remark" , "Trite or obvious remark" , "Commonplace remark, banal or trite" , "bromide" , "Commonplace remark uttered as if original" .)