Constrain president to provide transport for the young (9)
I believe the answer is:
pushchair
'provide transport for the young' is the definition.
I can't judge whether this definition defines the answer.
'constrain president' is the wordplay.
'constrain' becomes 'push' (I can't explain this - if you can you should believe this answer much more).
'president' becomes 'chair' (synonyms).
'push'+'chair'='PUSHCHAIR'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for pushchair that I've seen before include "Baby transport" , "Baby mover" , "transport for youngster" .)