Half-heartedly encourage hard nut, struggling during extremely tedious valuable pursuits? (8,5)

'valuable pursuits?' is the definition.
(a treasure hunt involves pursuing valuable things)

'half-heartedly encourage hard nut struggling during extremely tedious' is the wordplay.
I cannot quite see how this works, but
'hard' could be 'h' (abbreviation used in pencil classifications) and 'h' is present in the answer.
an anagram of 'nut' is 'unt' which is present in the answer.
The remaining letters 'treasures' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...