Mounting assistance (3,2)
I believe the answer is:
leg up
'assistance' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for leg up that I've seen before include "Help to climber" , "how to kick?" , "Assistance eg over stile" , "Help in mounting (eg, a horse)" , "Outcast" .)