Idolise a Queen over holding party (5)
I believe the answer is:
adore
'idolise' is the definition.
(I've seen this before)
'a queen over holding party' is the wordplay.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'over' says the letters should be written backwards.
'holding' means one lot of letters goes inside another.
'party' becomes 'do' (do can informally mean a party).
'er' written backwards gives 're'.
'a'+'re'='are'
'are' going around 'do' is 'ADORE'.
(Other definitions for adore that I've seen before include "Honour" , "Like a lot" , "Respect deeply" , "Love greatly" , "Love to distraction" .)