Helper turned to describe complicated graph for birth control (9)
I believe the answer is:
diaphragm
'birth control' is the definition.
(I know that diaphragm is a type of birth control)
'helper turned to describe complicated graph' is the wordplay.
'helper' becomes 'maid' (domestic servant).
'turned' is a reversal indicator.
'to describe' indicates putting letters inside.
'complicated' indicates anagramming the letters (a complex or confusing ordering of the letters).
'maid' backwards is 'diam'.
'graph' anagrammed gives 'phrag'.
'diam' going around 'phrag' is 'DIAPHRAGM'.
'for' acts as a link.
(Other definitions for diaphragm that I've seen before include "Flexible membrane" , "Partition between thorax and abdomen" , "Partitioning membrane" , "It separates the thorax from the abdomen" , "Thin dividing membrane" .)