Decide officially to draw the line (4)
I believe the answer is:
rule
I believe this clue is a triple definition!
'decide officially' is the first definition.
'rule' can be an answer for 'decide' (ruling is a kind of deciding). I'm not certain of the 'officially' bit.
'to draw' is the second definition.
(ruling is a kind of drawing)
'the' is a link.
'line' is the third definition.
(I've seen this in another clue)
Can you help me to learn more?
(Other definitions for rule that I've seen before include "Govern or control" , "Reign - law" , "Control using lure." , "Strip" , "Regulation, reign" .)