Was upset over politicians having no firm ground (6)
I believe the answer is:
swamps
'having no firm ground' is the definition.
I can't tell whether this definition defines the answer.
'was upset over politicians' is the wordplay.
'upset' indicates an anagram.
'over' says to put letters next to each other (in a down clue, some letters go over others).
'politicians' becomes 'MPs' (Members of Parliament).
'was' is an anagram of 'swa'.
'swa'+'mps'='SWAMPS'
Can you help me to learn more?
(Other definitions for swamps that I've seen before include "Seasonally-flooded low-lands" , "Seasonally flooding low lands" , "Drenches; fens" , "Seasonally flooding low-lands" , "Overwhelms in marshes" .)