Pleasant leader going to show reserve (3)
I believe the answer is:
ice
'show reserve' is the definition.
'ice' can be an answer for 'reserve' (both can mean aloofness). I'm not certain of the 'show' bit.
'pleasant leader' is the wordplay.
'pleasant' becomes 'ic' (I can't explain this - if you can you should believe this answer much more).
'leader' becomes 'e' (I've seen this in other clues).
'ic'+'e'='ICE'
'going to' is the link.
Can you help me to learn more?
(Other definitions for ice that I've seen before include "Reserve" , "Girl's best friends" , "Diamonds, colloquially" , "Solid H2O" , "Some number" .)