Suggestion of popular ruler protecting pound (7)
I believe the answer is:
inkling
'suggestion' is the definition.
(I've seen this before)
'popular ruler protecting pound' is the wordplay.
'popular' becomes 'in'.
'ruler' becomes 'king' (king is a kind of ruler**).
'protecting' is an insertion indicator.
'pound' becomes 'l'.
'king' placed around 'l' is 'kling'.
'in'+'kling'='INKLING'
'of' is the link.
(Other definitions for inkling that I've seen before include "Faint idea" , "Vague notion" , "Slight hint or suspicion" , "Vague idea" , "Vague suspicion" .)