Gross politician, one visiting boozer (7)
I believe the answer is:
lumpish
'gross' is the definition.
(thesaurus)
'politician one visiting boozer' is the wordplay.
'politician' becomes 'mp'.
'one' becomes 'i' (Roman numeral).
'visiting' indicates putting letters inside.
'boozer' becomes 'lush' ('lush' can be a synonym of 'boozer').
'mp'+'i'='mpi'
'mpi' placed within 'lush' is 'LUMPISH'.
(Other definitions for lumpish that I've seen before include "Ungainly" , "misshapen" .)