Selection of candidates left over with operation being put back (4)
I believe the answer is:
pool
'selection of candidates left' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'over with operation being put back' is the wordplay.
I cannot really understand how this works, but
'over' could be 'o' (cricket abbreviation) and 'o' is found in the answer.
'being' could be 'pol' (pol is a kind of being) and 'pol' is found in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pool that I've seen before include "17 - small stretch of water" , "game indoors" , "American game resembling snooker" , "Bellini opera" , "Ball game - small body of water" .)