Bit of exercise for the chickens (3)
I believe the answer is:
run
'bit of exercise' is the definition.
'run' can be an answer for 'exercise'. I am not sure about the 'bit of' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for run that I've seen before include "A point scored in cricket" , "On the . . . - fleeing from pursuit" , "faster pace needed" , "Enter a race" , "Manage, operate" .)