Uncomfortable position pinched bottom (3,4)
I believe the answer is:
hot seat
'uncomfortable position' is the definition.
(I've seen this in another clue)
'pinched bottom' is the wordplay.
'pinched' becomes 'hot' (I am not sure about this - if you are sure you should believe this answer much more).
'bottom' becomes 'seat' (synonyms).
'hot'+'seat'='HOT SEAT'
Can you help me to learn more?
(Other definitions for hot seat that I've seen before include "Situation of responsibility or danger" , "Hates to be in difficult position" , "from which bottom quick to rise?" , "new constituency" , "Chair for person with difficult responsibility" .)