Outstanding university pad in Barking (6)
I believe the answer is:
unpaid
'outstanding' is the definition.
('unpaid' can be similar in meaning to 'outstanding')
'university pad in barking' is the wordplay.
'university' becomes 'u'.
'barking' is an anagram indicator (UK slang for mad).
'pad'+'in'='padin'
'padin' is an anagram of 'npaid'.
'u'+'npaid'='UNPAID'
(Other definitions for unpaid that I've seen before include "Overdue" , "Not yet remunerated" , "Without reward" , "Outstanding, owing" , "Not give wages" .)