Inconclusive list to be shortened before end (13)
I believe the answer is:
indeterminate
'inconclusive' is the definition.
(similar in meaning)
'list to be shortened before end' is the wordplay.
I cannot really understand how this works, but
'before' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
'end' could be 'terminate' (synonyms) and 'terminate' is located in the answer.
The remaining letters 'ind' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for indeterminate that I've seen before include "not exactly fixed" , "Unfixed, uncertain" , "uncertain result?" , "Inconclusive" , "Having no fixed value" .)