A pal around Oriel, struggling to improve (10)
I believe the answer is:
ameliorate
'improve' is the definition.
('ameliorate' can be a synonym of 'improve')
'a pal around oriel struggling' is the wordplay.
'pal' becomes 'mate' (I've seen this before).
'around' indicates putting letters inside.
'struggling' indicates an anagram.
'oriel' with letters rearranged gives 'elior'.
'mate' enclosing 'elior' is 'meliorate'.
'a'+'meliorate'='AMELIORATE'
'to' is the link.
(Other definitions for ameliorate that I've seen before include "seen to improve" , "Become better" , "Make (a bad thing) better" , "Make (something) better" .)