Hint coming from popular monarch, about 50 (7)
I believe the answer is:
inkling
'hint' is the definition.
(I've seen this before)
'popular monarch about 50' is the wordplay.
'popular' becomes 'in' (something that's 'in' is fashionable).
'monarch' becomes 'king' (male monarch).
'about' means one lot of letters goes inside another.
'50' becomes 'l' (Roman numeral).
'king' enclosing 'l' is 'kling'.
'in'+'kling'='INKLING'
'coming from' acts as a link.
(Other definitions for inkling that I've seen before include "Clue" , "Vague notion" , "Faint idea" , "Vague idea" , "Vague suspicion" .)