Reason for taking half the cigars back to Oscar in Peruvian capital (5)
I believe the answer is:
logic
'reason' is the definition.
(logic is using reason)
'taking half the cigars back to oscar in peruvian capital' is the wordplay.
'taking half' means to take half the letters.
'back' is a reversal indicator.
'to' says to put letters next to each other (I've seen this in other clues).
'oscar in peruvian capital' becomes 'lo' (I can't explain this - if you can you should believe this answer much more).
'cigars' with half the letters taken is 'cig'.
'cig' in reverse letter order is 'gic'.
'gic' put after 'lo' is 'LOGIC'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for logic that I've seen before include "Science of correct reasoning" , "Sound reasoning" , "good sense" , "The science of reasoning from cause to effect" , "Rigorous reasoning" .)