Swim club here ejecting old royal (5)
I believe the answer is:
bathe
'swim' is the definition.
(bathe can mean to swim)
'club here ejecting old royal' is the wordplay.
'club' becomes 'bat' (as in sporting equipment).
'ejecting' suggests deleting specific letters.
'old royal' becomes 'ER' (Elizabeth Regina ie Queen Elizabeth).
'here' with 'er' taken out is 'he'.
'bat'+'he'='BATHE'
(Other definitions for bathe that I've seen before include "Become immersed in" , "Swim or paddle" , "plunge" , "Wash by immersion" , "Wash, soak" .)