Healthy reward a few gathered after clean-up (4,3)
I believe the answer is:
tidy sum
'healthy reward a few' is the definition.
I can't judge whether this defines the answer.
'gathered after clean-up' is the wordplay.
'gathered' becomes 'sum' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'after' is a charade indicator (letters next to each other).
'clean up' becomes 'tidy' (synonyms).
'sum' after 'tidy' is 'TIDY SUM'.
Can you help me to learn more?
(Other definitions for tidy sum that I've seen before include "A lot of money" , "Considerable amount" .)