Logically decide what could produce a snore (6,3)
I believe the answer is:
reason out
'logically decide' is the definition.
(to reason out is to decide using reason)
'what could produce a snore' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
an anagram of 'snore' is 'reson' which is located in the remaining letters.
The remaining letters 'out' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
(Another definition for reason out that I've seen is " Think through".)