Make amends when catching cold right now (2,4)
I believe the answer is:
at once
'right now' is the definition.
(I've seen this in another clue)
'make amends when catching cold' is the wordplay.
I cannot really understand how this works, but
'when' could be 'once' (synonyms) and 'once' is found in the answer.
The remaining letters 'at' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for at once that I've seen before include "Right now, this instant" , "'Without delay (2,4)'" , "This instant, without delay" , "Immediately, without delay" , "from the kick-off" .)