Cool, trick answer entered upside down (5)
I believe the answer is:
aloof
'cool trick' is the definition.
'aloof' can be an answer for 'cool' (I've seen this in another clue). I'm not certain of the 'trick' bit.
'answer entered upside down' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'entered upside down' becomes 'loof' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'loof'='ALOOF'
Can you help me to learn more?
(Other definitions for aloof that I've seen before include "Standoffish like a fool" , "Unpleasantly cold" , "apart from all else" , "Distant in manner" , "Unapproachable, distant" .)