Arduous and extremely unusual to get around Phil (6)
I believe the answer is:
uphill
'arduous' is the definition.
(I've seen this in another clue)
'extremely unusual to get around phil' is the wordplay.
'extremely' says to hollow out the word (remove centre letters) (only the extremes of the word are used).
'to get around' indicates putting letters inside.
'unusual' with its centre removed is 'ul'.
'ul' placed around 'phil' is 'UPHILL'.
'and' is the link.
(Other definitions for uphill that I've seen before include "Difficult, like steep slope" , "Ascending -- sort of struggle" , "This going is tough, but climb on" , "Ascending - arduous" , "The harder way to walk" .)