Knock dinner up to try to prevent collapse (8)
I believe the answer is:
underpin
'try to prevent collapse' is the definition.
I can't judge whether this definition defines the answer.
'knock dinner up' is the wordplay.
'knock' indicates anagramming the letters.
'dinner'+'up'='dinnerup'
'dinnerup' is an anagram of 'UNDERPIN'.
'to' is the link.
Can you help me to learn more?
(Other definitions for underpin that I've seen before include "Support or strengthen from beneath" , "buttress" , "Prop up with nun pride" , "corroborate" , "Form the basis for" .)