Monarch likely to establish a line? (5)
I believe the answer is:
ruler
'monarch' is the definition.
(I've seen this before)
'likely to establish a line?' is the wordplay.
I cannot quite understand how this works, but
'line?' could be 'rule' (I've seen this in another clue) and 'rule' is located in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ruler that I've seen before include "Straight line could come from this" , "King, president etc." , "Monarch or measure" , "One for drawing lines" , "One exercising control" .)