To some extent skilful, entrant advanced (4)
I believe the answer is:
lent
'advanced' is the definition.
(advance can mean to lend)
'to some extent skilful entrant' is the wordplay.
'to some extent' indicates the answer is hidden within the clue (I've seen 'extent of' mean this (I've seen this in other clues)).
'LENT' is hidden in the letters of 'skilful entrant'.
(Other definitions for lent that I've seen before include "Pre-Easter period" , "Period from Ash Wednesday to Easter" , "Period of fasting" , "From Ash Wednesday to Holy Saturday" , "Christian period of abstinence" .)