Not happy with rigid state at the top (5)
I believe the answer is:
upset
'state at the top' is the definition.
I can't tell whether this defines the answer.
'not happy with rigid' is the wordplay.
'not happy' becomes 'up' (I've seen this in other clues. I am not sure about the 'not' bit.).
'with' means one lot of letters go next to another.
'rigid' becomes 'set' (synonyms).
'up'+'set'='UPSET'
Can you help me to learn more?
(Other definitions for upset that I've seen before include "Overturn - worry" , "Disturb(ance)" , "Overturn or discompose" , "Make unhappy; disrupt" , "Disturbed or overturned" .)