Feeble Fed's quietly pursuing cartel at last (4)
I believe the answer is:
limp
'feeble' is the definition.
(I've seen this before)
'fed's quietly pursuing cartel at last' is the wordplay.
'fed's quietly' becomes 'imp' (I am not sure about this - if you are sure you should believe this answer much more).
'pursuing' is a charade indicator (letters next to each other).
'at last' says to take the final letters.
The final letter of 'cartel' is 'l'.
'imp' after 'l' is 'LIMP'.
Can you help me to learn more?
(Other definitions for limp that I've seen before include "Floppy" , "Walk haltingly" , "Uneven way of walking" , "Walk with difficulty" , "Walk unevenly; not stiff" .)