Refuse to admit beard is unkempt (5)
I believe the answer is:
debar
'refuse to admit' is the definition.
(I've seen this before)
'beard is unkempt' is the wordplay.
'is unkempt' indicates an anagram.
'beard' is an anagram of 'DEBAR'.
(Other definitions for debar that I've seen before include "Exclude, prohibit" , "Blackball" , "Exclude (from doing something)" , "Refuse to admit" , "Shut out, preclude" .)