Mole good on queen (4)
I believe the answer is:
pier
'mole' is the definition.
(thesaurus)
'good on queen' is the wordplay.
'good' becomes 'pi' (I've seen this in other clues).
'on' says to put letters next to each other.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'pi'+'er'='PIER'
(Other definitions for pier that I've seen before include "Breakwater; arch pillar" , "Quay" , "Seaside attraction" , "Support for two adjacent bridge spans" , "Building projecting into the sea" .)