Denies gag is improper and separate (9)
I believe the answer is:
disengage
'separate' is the definition.
(I've seen this in another clue)
'denies gag is improper' is the wordplay.
'is improper' is an anagram indicator.
'denies'+'gag'='deniesgag'
'deniesgag' anagrammed gives 'DISENGAGE'.
'and' is the link.
(Other definitions for disengage that I've seen before include "free" , "Withdraw" , "Separate, release, detach" , "Remove (troops) from a conflict" .)