Weak US intelligence service maintaining average returns (7)
I believe the answer is:
'weak' is the definition.
(similar in meaning)
'service maintaining average returns' is the wordplay.
'service' becomes 'cia' (I can't justify this - if you can you should believe this answer much more).
'maintaining' means one lot of letters goes inside another.
'average' becomes 'mean' (type of average).
'returns' shows that the letters should be reversed in order.
'cia' placed around 'mean' is 'cimeana'.
'cimeana' back-to-front is 'ANAEMIC'.
'us intelligence' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for anaemic that I've seen before include "Suffering from a lack of red blood cells" , "Pale, weak in colour" , "Member of a pride" , "bloody poor" , "Lacking vigour as in a cinema" .)