Making equine data jockey will be wanting (10)
I believe the answer is:
inadequate
'be wanting' is the definition.
(similar in meaning)
'making equine data' is the wordplay.
'making' is an anagram indicator.
'equine'+'data'='equinedata'
'equinedata' is an anagram of 'INADEQUATE'.
'jockey will' is the 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 inadequate that I've seen before include "lacking" , "Found wanting" , "Insufficient" , "Falling short of requirements" , "Short of what is required" .)