Some badger's lair taken up for tests (6)
I believe the answer is:
trials
'tests' is the definition.
('trial' can be a synonym of 'test')
'some badger's lair taken up' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'up' is a reversal indicator (in down clue: letters go upwards).
'slairt' can be found hidden inside 'badgers lair taken'.
'slairt' in reverse letter order is 'TRIALS'.
'for' is the link.
(Other definitions for trials that I've seen before include "Attempts" , "Tribulations" , "Court hearings or experiments" , "Legal proceedings or tests of endurance" , "Court cases or ordeals" .)