Support premier accepting Republican crown (7)
I believe the answer is:
treetop
'crown' is the definition.
(synonyms)
'support premier accepting republican' is the wordplay.
'support' becomes 'tee' (tee is a kind of support).
'premier' becomes 'top' (I've seen this in another clue).
'accepting' is an insertion indicator (inserted letters are accepted).
'republican' becomes 'R' (abbreviation in US politics).
'tee'+'top'='teetop'
'teetop' placed around 'r' is 'TREETOP'.
(Other definitions for treetop that I've seen before include "` `Rockaby baby on a .......' '" , "To Peter (anag)" , "Highest branch location" , "Crown; rock-a-bye baby here" , "High point of a plane, for example" .)