By a slow team (9)
I believe the answer is:
alongside
'by' is the definition.
(I've seen this before)
'a slow team' is the wordplay.
'a slow' becomes 'along' (I can't justify this - if you can you should believe this answer much more).
'team' becomes 'side' (both can mean a sports team).
'along'+'side'='ALONGSIDE'
Can you help me to learn more?
(Other definitions for alongside that I've seen before include "Adjacent to" , "close to a bank" , "Aligned so as to be next to, as ship moored to pier" , "Age-old sin (anag.)" , "Side by side" .)