One way to arrive at a conclusion? (1,5,2,2,3)
I believe the answer is:
a means to an end
'one' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'way to arrive at a conclusion?' is the wordplay.
I cannot really see how this works, but
'way' could be 'means' (synonyms) and 'means' is present in the answer.
'to' is found in the answer.
'a' could be 'an' and 'an' is found in the answer.
'conclusion?' could be 'end' (something's conclusion is its end) and 'end' is present in the answer.
A single letter 'a' remains 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?
(Another definition for a means to an end that I've seen is " Not important in itself, but useful to the whole".)