Finish base over apex (3,2)
I believe the answer is:
end up
'finish base over apex' is the definition.
'end up' can be an answer for 'finish' (synonyms). I'm not sure about the 'base over apex' bit.
'finish base over' is the wordplay.
I cannot quite see how this works, but
'finish' could be 'end' (synonyms) and 'end' is found within the answer.
'over' could be 'up' (e.g. if your time is up it is over) and 'up' is found within the answer.
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 end up that I've seen before include "Ultimately become" , "head first" , "finally arrive" , "finish ahead" , "Eventually become" .)