Hairy-footed midget’s pastime, mostly just what’s needed (6)
I believe the answer is:
hobbit
'hairy-footed midget's' is the definition.
(type of small humanoid in The Lord of the Rings)
'pastime mostly just what's needed' is the wordplay.
'pastime' becomes 'hobby' (hobby is a kind of pastime).
'mostly' means to remove the last letter.
'just what's needed' becomes 'it' (as in 'that's it!').
'hobby' with its final letter taken off is 'hobb'.
'hobb'+'it'='HOBBIT'
(Other definitions for hobbit that I've seen before include "Tolkien's hole-dweller" , "Creature as Bilbo Baggins" , "Tolkien's halfling" , "Little fellow" , "Tolkien's inhabitant of the lands of Middle-earth" .)