Blood banks to control rough rate (6)
I believe the answer is:
claret
'blood banks' is the definition.
'claret' can be an answer for 'blood' (claret can informally mean blood). I am not sure about the 'banks' bit.
'control rough rate' is the wordplay.
'control' becomes 'cl' (I am not sure about this - if you are sure you should believe this answer much more).
'rough' indicates an anagram (a rough or broken ordering of the letters).
'rate' anagrammed gives 'aret'.
'cl'+'aret'='CLARET'
'to' is the link.
Can you help me to learn more?
(Other definitions for claret that I've seen before include "Deep purplish-red" , "Purplish-red - blood" , "vessel might contain this?" , "Deep red colour" , "Irish county starts the wine" .)