Republican dons ready for economic collapse (5)
I believe the answer is:
crash
'economic collapse' is the definition.
(I've seen this before)
'republican dons ready' is the wordplay.
'republican' becomes 'R' (political abbreviation).
'dons' means one lot of letters goes inside another (don means to wear or put on).
'ready' becomes 'cash' (ready can informally mean cash).
'r' going inside 'cash' is 'CRASH'.
'for' acts as a link.
(Other definitions for crash that I've seen before include "Impact" , "Planned quickly for emergency" , "Bang" , "Economic collapse" , "Car accident" .)