Train during parade transports leader of carnival (8)
I believe the answer is:
instruct
'train' is the definition.
(I know that train is a more specific form of the action instruct)
'during parade transports leader of carnival' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'parade' becomes 'strut' (as in strutting or parading around).
'transports' indicates putting letters inside.
'leader of' indicates taking the first letters.
The first letter of 'carnival' is 'c'.
'strut' going around 'c' is 'struct'.
'in'+'struct'='INSTRUCT'
(Other definitions for instruct that I've seen before include "Impart skills or knowledge to" , "Give legal orders" , "Command; teach" , "Inform or authorise" , "Tutor; order" .)