Hormone secreted by the pancreas (7)
I believe the answer is:
insulin
'hormone secreted by the pancreas' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for insulin that I've seen before include "Hormone that controls the body's sugar absorption" , "Sugar-controlling hormone" , "Hormone or medication controlling body's sugar level" , "Pancreatic hormone" , "Hormone - nil in us (anag)" .)