Transport for Ollie’s fish food (10)
I believe the answer is:
skateboard
'transport' is the definition.
(I have seen 'Wheeled transport ' mean 'skateboard' so perhaps 'transport' could also mean 'skateboard')
'fish food' is the wordplay.
'fish' becomes 'skate' (skate is a kind of fish).
'food' becomes 'board' (board is a kind of food).
'skate'+'board'='SKATEBOARD'
'for ollie's' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for skateboard that I've seen before include "which carries playful youth along" , "One rolls along" , "Wheeled plaything" , "Small wheeled platform on which person can scoot and ride" , "Young person's wheeled transport" .)