Did suffer going round in that new red number (9)
I believe the answer is:
underwent
'did suffer going round in that new red number' is the definition.
'underwent' can be an answer for 'did suffer'. I'm not sure about the rest of the definition.
'round in that new red number' is the wordplay.
'round' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'tnewrednu' is hidden within 'that new red number'.
'tnewrednu' in reverse letter order is 'UNDERWENT'.
(Other definitions for underwent that I've seen before include "Experienced; bore" , "Was subjected to" .)